{"dataType": "CVE_RECORD", "dataVersion": "5.1", "cveMetadata": {"cveId": "CVE-2021-47656", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-02-26T01:48:21.521Z", "datePublished": "2025-02-26T01:54:20.069Z", "dateUpdated": "2025-02-27T18:02:30.510Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2025-02-26T01:54:20.069Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\njffs2: fix use-after-free in jffs2_clear_xattr_subsystem\n\nWhen we mount a jffs2 image, assume that the first few blocks of\nthe image are normal and contain at least one xattr-related inode,\nbut the next block is abnormal. As a result, an error is returned\nin jffs2_scan_eraseblock(). jffs2_clear_xattr_subsystem() is then\ncalled in jffs2_build_filesystem() and then again in\njffs2_do_fill_super().\n\nFinally we can observe the following report:\n ==================================================================\n BUG: KASAN: use-after-free in jffs2_clear_xattr_subsystem+0x95/0x6ac\n Read of size 8 at addr ffff8881243384e0 by task mount/719\n\n Call Trace:\n dump_stack+0x115/0x16b\n jffs2_clear_xattr_subsystem+0x95/0x6ac\n jffs2_do_fill_super+0x84f/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n mtd_get_sb+0x254/0x400\n mtd_get_sb_by_nr+0x4f/0xd0\n get_tree_mtd+0x498/0x840\n jffs2_get_tree+0x25/0x30\n vfs_get_tree+0x8d/0x2e0\n path_mount+0x50f/0x1e50\n do_mount+0x107/0x130\n __se_sys_mount+0x1c5/0x2f0\n __x64_sys_mount+0xc7/0x160\n do_syscall_64+0x45/0x70\n entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\n Allocated by task 719:\n kasan_save_stack+0x23/0x60\n __kasan_kmalloc.constprop.0+0x10b/0x120\n kasan_slab_alloc+0x12/0x20\n kmem_cache_alloc+0x1c0/0x870\n jffs2_alloc_xattr_ref+0x2f/0xa0\n jffs2_scan_medium.cold+0x3713/0x4794\n jffs2_do_mount_fs.cold+0xa7/0x2253\n jffs2_do_fill_super+0x383/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n [...]\n\n Freed by task 719:\n kmem_cache_free+0xcc/0x7b0\n jffs2_free_xattr_ref+0x78/0x98\n jffs2_clear_xattr_subsystem+0xa1/0x6ac\n jffs2_do_mount_fs.cold+0x5e6/0x2253\n jffs2_do_fill_super+0x383/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n [...]\n\n The buggy address belongs to the object at ffff8881243384b8\n which belongs to the cache jffs2_xattr_ref of size 48\n The buggy address is located 40 bytes inside of\n 48-byte region [ffff8881243384b8, ffff8881243384e8)\n [...]\n ==================================================================\n\nThe triggering of the BUG is shown in the following stack:\n-----------------------------------------------------------\njffs2_fill_super\n jffs2_do_fill_super\n jffs2_do_mount_fs\n jffs2_build_filesystem\n jffs2_scan_medium\n jffs2_scan_eraseblock <--- ERROR\n jffs2_clear_xattr_subsystem <--- free\n jffs2_clear_xattr_subsystem <--- free again\n-----------------------------------------------------------\n\nAn error is returned in jffs2_do_mount_fs(). If the error is returned\nby jffs2_sum_init(), the jffs2_clear_xattr_subsystem() does not need to\nbe executed. If the error is returned by jffs2_build_filesystem(), the\njffs2_clear_xattr_subsystem() also does not need to be executed again.\nSo move jffs2_clear_xattr_subsystem() from 'out_inohash' to 'out_root'\nto fix this UAF problem."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/jffs2/fs.c"], "versions": [{"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "9150cb625b46f68d524f4cfd491f1aafc23e10a9", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "3bd2454162ec6bbb5503233c804fce6e4b6dcec5", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "c3b07c875fa8f906f932976460fd14798596f101", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "30bf7244acf32f19cb722c39f7bc1c2a9f300422", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "7bb7428dd73991bf4b3a7a61b493ca50046c2b13", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "7a75740206af5f17e9f3efa384211cba70213da1", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "22327bd7988f21de3a53c1373f3b81542bfe1f44", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "8c0f024f29e055840a5a89fe23b96ae3f921afed", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "4c7c44ee1650677fbe89d86edbad9497b7679b5c", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/jffs2/fs.c"], "versions": [{"version": "2.6.18", "status": "affected"}, {"version": "0", "lessThan": "2.6.18", "status": "unaffected", "versionType": "semver"}, {"version": "4.9.311", "lessThanOrEqual": "4.9.*", "status": "unaffected", "versionType": "semver"}, {"version": "4.14.276", "lessThanOrEqual": "4.14.*", "status": "unaffected", "versionType": "semver"}, {"version": "4.19.238", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.4.189", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.110", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.33", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.16.19", "lessThanOrEqual": "5.16.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.17.2", "lessThanOrEqual": "5.17.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.18", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "references": [{"url": "https://git.kernel.org/stable/c/9150cb625b46f68d524f4cfd491f1aafc23e10a9"}, {"url": "https://git.kernel.org/stable/c/3bd2454162ec6bbb5503233c804fce6e4b6dcec5"}, {"url": "https://git.kernel.org/stable/c/c3b07c875fa8f906f932976460fd14798596f101"}, {"url": "https://git.kernel.org/stable/c/30bf7244acf32f19cb722c39f7bc1c2a9f300422"}, {"url": "https://git.kernel.org/stable/c/7bb7428dd73991bf4b3a7a61b493ca50046c2b13"}, {"url": "https://git.kernel.org/stable/c/7a75740206af5f17e9f3efa384211cba70213da1"}, {"url": "https://git.kernel.org/stable/c/22327bd7988f21de3a53c1373f3b81542bfe1f44"}, {"url": "https://git.kernel.org/stable/c/8c0f024f29e055840a5a89fe23b96ae3f921afed"}, {"url": "https://git.kernel.org/stable/c/4c7c44ee1650677fbe89d86edbad9497b7679b5c"}], "title": "jffs2: fix use-after-free in jffs2_clear_xattr_subsystem", "x_generator": {"engine": "bippy-5f407fcff5a0"}}, "adp": [{"metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"id": "CVE-2021-47656", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2025-02-27T17:59:35.381270Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-416", "description": "CWE-416 Use After Free"}]}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-02-27T18:02:30.510Z"}}]}}

{"dataType": "CVE_RECORD", "dataVersion": "5.1", "cveMetadata": {"cveId": "CVE-2021-47656", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-02-26T01:48:21.521Z", "datePublished": "2025-02-26T01:54:20.069Z", "dateUpdated": "2025-02-27T18:02:30.510Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2025-02-26T01:54:20.069Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\njffs2: fix use-after-free in jffs2_clear_xattr_subsystem\n\nWhen we mount a jffs2 image, assume that the first few blocks of\nthe image are normal and contain at least one xattr-related inode,\nbut the next block is abnormal. As a result, an error is returned\nin jffs2_scan_eraseblock(). jffs2_clear_xattr_subsystem() is then\ncalled in jffs2_build_filesystem() and then again in\njffs2_do_fill_super().\n\nFinally we can observe the following report:\n ==================================================================\n BUG: KASAN: use-after-free in jffs2_clear_xattr_subsystem+0x95/0x6ac\n Read of size 8 at addr ffff8881243384e0 by task mount/719\n\n Call Trace:\n dump_stack+0x115/0x16b\n jffs2_clear_xattr_subsystem+0x95/0x6ac\n jffs2_do_fill_super+0x84f/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n mtd_get_sb+0x254/0x400\n mtd_get_sb_by_nr+0x4f/0xd0\n get_tree_mtd+0x498/0x840\n jffs2_get_tree+0x25/0x30\n vfs_get_tree+0x8d/0x2e0\n path_mount+0x50f/0x1e50\n do_mount+0x107/0x130\n __se_sys_mount+0x1c5/0x2f0\n __x64_sys_mount+0xc7/0x160\n do_syscall_64+0x45/0x70\n entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\n Allocated by task 719:\n kasan_save_stack+0x23/0x60\n __kasan_kmalloc.constprop.0+0x10b/0x120\n kasan_slab_alloc+0x12/0x20\n kmem_cache_alloc+0x1c0/0x870\n jffs2_alloc_xattr_ref+0x2f/0xa0\n jffs2_scan_medium.cold+0x3713/0x4794\n jffs2_do_mount_fs.cold+0xa7/0x2253\n jffs2_do_fill_super+0x383/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n [...]\n\n Freed by task 719:\n kmem_cache_free+0xcc/0x7b0\n jffs2_free_xattr_ref+0x78/0x98\n jffs2_clear_xattr_subsystem+0xa1/0x6ac\n jffs2_do_mount_fs.cold+0x5e6/0x2253\n jffs2_do_fill_super+0x383/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n [...]\n\n The buggy address belongs to the object at ffff8881243384b8\n which belongs to the cache jffs2_xattr_ref of size 48\n The buggy address is located 40 bytes inside of\n 48-byte region [ffff8881243384b8, ffff8881243384e8)\n [...]\n ==================================================================\n\nThe triggering of the BUG is shown in the following stack:\n-----------------------------------------------------------\njffs2_fill_super\n jffs2_do_fill_super\n jffs2_do_mount_fs\n jffs2_build_filesystem\n jffs2_scan_medium\n jffs2_scan_eraseblock <--- ERROR\n jffs2_clear_xattr_subsystem <--- free\n jffs2_clear_xattr_subsystem <--- free again\n-----------------------------------------------------------\n\nAn error is returned in jffs2_do_mount_fs(). If the error is returned\nby jffs2_sum_init(), the jffs2_clear_xattr_subsystem() does not need to\nbe executed. If the error is returned by jffs2_build_filesystem(), the\njffs2_clear_xattr_subsystem() also does not need to be executed again.\nSo move jffs2_clear_xattr_subsystem() from 'out_inohash' to 'out_root'\nto fix this UAF problem."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/jffs2/fs.c"], "versions": [{"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "9150cb625b46f68d524f4cfd491f1aafc23e10a9", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "3bd2454162ec6bbb5503233c804fce6e4b6dcec5", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "c3b07c875fa8f906f932976460fd14798596f101", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "30bf7244acf32f19cb722c39f7bc1c2a9f300422", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "7bb7428dd73991bf4b3a7a61b493ca50046c2b13", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "7a75740206af5f17e9f3efa384211cba70213da1", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "22327bd7988f21de3a53c1373f3b81542bfe1f44", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "8c0f024f29e055840a5a89fe23b96ae3f921afed", "status": "affected", "versionType": "git"}, {"version": "aa98d7cf59b5b0764d3502662053489585faf2fe", "lessThan": "4c7c44ee1650677fbe89d86edbad9497b7679b5c", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/jffs2/fs.c"], "versions": [{"version": "2.6.18", "status": "affected"}, {"version": "0", "lessThan": "2.6.18", "status": "unaffected", "versionType": "semver"}, {"version": "4.9.311", "lessThanOrEqual": "4.9.*", "status": "unaffected", "versionType": "semver"}, {"version": "4.14.276", "lessThanOrEqual": "4.14.*", "status": "unaffected", "versionType": "semver"}, {"version": "4.19.238", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.4.189", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.110", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.33", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.16.19", "lessThanOrEqual": "5.16.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.17.2", "lessThanOrEqual": "5.17.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.18", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "references": [{"url": "https://git.kernel.org/stable/c/9150cb625b46f68d524f4cfd491f1aafc23e10a9"}, {"url": "https://git.kernel.org/stable/c/3bd2454162ec6bbb5503233c804fce6e4b6dcec5"}, {"url": "https://git.kernel.org/stable/c/c3b07c875fa8f906f932976460fd14798596f101"}, {"url": "https://git.kernel.org/stable/c/30bf7244acf32f19cb722c39f7bc1c2a9f300422"}, {"url": "https://git.kernel.org/stable/c/7bb7428dd73991bf4b3a7a61b493ca50046c2b13"}, {"url": "https://git.kernel.org/stable/c/7a75740206af5f17e9f3efa384211cba70213da1"}, {"url": "https://git.kernel.org/stable/c/22327bd7988f21de3a53c1373f3b81542bfe1f44"}, {"url": "https://git.kernel.org/stable/c/8c0f024f29e055840a5a89fe23b96ae3f921afed"}, {"url": "https://git.kernel.org/stable/c/4c7c44ee1650677fbe89d86edbad9497b7679b5c"}], "title": "jffs2: fix use-after-free in jffs2_clear_xattr_subsystem", "x_generator": {"engine": "bippy-5f407fcff5a0"}}, "adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"id": "CVE-2021-47656", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2025-02-27T17:59:35.381270Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-416", "description": "CWE-416 Use After Free"}]}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-02-27T17:59:36.648Z"}}]}}

{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "EB5E8137-261D-4D1B-A71B-A70EE8FD2C08", "versionEndExcluding": "4.9.311", "versionStartIncluding": "2.6.18", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "6D9B028C-6313-47F9-94B7-5F8122345E49", "versionEndExcluding": "4.14.276", "versionStartIncluding": "4.10", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "FA28527A-11D3-41D2-9C4C-ECAC0D6A4A2D", "versionEndExcluding": "4.19.238", "versionStartIncluding": "4.15", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "8CB6E8F5-C2B1-46F3-A807-0F6104AC340F", "versionEndExcluding": "5.4.189", "versionStartIncluding": "4.20", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "91D3BFD0-D3F3-4018-957C-96CCBF357D79", "versionEndExcluding": "5.10.110", "versionStartIncluding": "5.5", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "27C42AE8-B387-43E2-938A-E1C8B40BE6D5", "versionEndExcluding": "5.15.33", "versionStartIncluding": "5.11", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "20C43679-0439-405A-B97F-685BEE50613B", "versionEndExcluding": "5.16.19", "versionStartIncluding": "5.16", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "210C679C-CF84-44A3-8939-E629C87E54BF", "versionEndExcluding": "5.17.2", "versionStartIncluding": "5.17", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\njffs2: fix use-after-free in jffs2_clear_xattr_subsystem\n\nWhen we mount a jffs2 image, assume that the first few blocks of\nthe image are normal and contain at least one xattr-related inode,\nbut the next block is abnormal. As a result, an error is returned\nin jffs2_scan_eraseblock(). jffs2_clear_xattr_subsystem() is then\ncalled in jffs2_build_filesystem() and then again in\njffs2_do_fill_super().\n\nFinally we can observe the following report:\n ==================================================================\n BUG: KASAN: use-after-free in jffs2_clear_xattr_subsystem+0x95/0x6ac\n Read of size 8 at addr ffff8881243384e0 by task mount/719\n\n Call Trace:\n dump_stack+0x115/0x16b\n jffs2_clear_xattr_subsystem+0x95/0x6ac\n jffs2_do_fill_super+0x84f/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n mtd_get_sb+0x254/0x400\n mtd_get_sb_by_nr+0x4f/0xd0\n get_tree_mtd+0x498/0x840\n jffs2_get_tree+0x25/0x30\n vfs_get_tree+0x8d/0x2e0\n path_mount+0x50f/0x1e50\n do_mount+0x107/0x130\n __se_sys_mount+0x1c5/0x2f0\n __x64_sys_mount+0xc7/0x160\n do_syscall_64+0x45/0x70\n entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\n Allocated by task 719:\n kasan_save_stack+0x23/0x60\n __kasan_kmalloc.constprop.0+0x10b/0x120\n kasan_slab_alloc+0x12/0x20\n kmem_cache_alloc+0x1c0/0x870\n jffs2_alloc_xattr_ref+0x2f/0xa0\n jffs2_scan_medium.cold+0x3713/0x4794\n jffs2_do_mount_fs.cold+0xa7/0x2253\n jffs2_do_fill_super+0x383/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n [...]\n\n Freed by task 719:\n kmem_cache_free+0xcc/0x7b0\n jffs2_free_xattr_ref+0x78/0x98\n jffs2_clear_xattr_subsystem+0xa1/0x6ac\n jffs2_do_mount_fs.cold+0x5e6/0x2253\n jffs2_do_fill_super+0x383/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n [...]\n\n The buggy address belongs to the object at ffff8881243384b8\n which belongs to the cache jffs2_xattr_ref of size 48\n The buggy address is located 40 bytes inside of\n 48-byte region [ffff8881243384b8, ffff8881243384e8)\n [...]\n ==================================================================\n\nThe triggering of the BUG is shown in the following stack:\n-----------------------------------------------------------\njffs2_fill_super\n jffs2_do_fill_super\n jffs2_do_mount_fs\n jffs2_build_filesystem\n jffs2_scan_medium\n jffs2_scan_eraseblock <--- ERROR\n jffs2_clear_xattr_subsystem <--- free\n jffs2_clear_xattr_subsystem <--- free again\n-----------------------------------------------------------\n\nAn error is returned in jffs2_do_mount_fs(). If the error is returned\nby jffs2_sum_init(), the jffs2_clear_xattr_subsystem() does not need to\nbe executed. If the error is returned by jffs2_build_filesystem(), the\njffs2_clear_xattr_subsystem() also does not need to be executed again.\nSo move jffs2_clear_xattr_subsystem() from 'out_inohash' to 'out_root'\nto fix this UAF problem."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: jffs2: se corrige el use-after-free en jffs2_clear_xattr_subsystem Cuando montamos una imagen jffs2, asumimos que los primeros bloques de la imagen son normales y contienen al menos un inodo relacionado con xattr, pero el siguiente bloque es anormal. Como resultado, se devuelve un error en jffs2_scan_eraseblock(). Luego se llama a jffs2_clear_xattr_subsystem() en jffs2_build_filesystem() y luego nuevamente en jffs2_do_fill_super(). Finalmente podemos observar el siguiente reporte: ======================================================================= ERROR: KASAN: use-after-free en jffs2_clear_xattr_subsystem+0x95/0x6ac Lectura de tama\u00f1o 8 en la direcci\u00f3n ffff8881243384e0 por la tarea mount/719 Rastreo de llamadas: dump_stack+0x115/0x16b jffs2_clear_xattr_subsystem+0x95/0x6ac jffs2_do_fill_super+0x84f/0xc30 jffs2_fill_super+0x2ea/0x4c0 mtd_get_sb+0x254/0x400 mtd_get_sb_by_nr+0x4f/0xd0 get_tree_mtd+0x498/0x840 jffs2_get_tree+0x25/0x30 vfs_get_tree+0x8d/0x2e0 path_mount+0x50f/0x1e50 do_mount+0x107/0x130 __se_sys_mount+0x1c5/0x2f0 __x64_sys_mount+0xc7/0x160 do_syscall_64+0x45/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Asignado por la tarea 719: kasan_save_stack+0x23/0x60 __kasan_kmalloc.constprop.0+0x10b/0x120 kasan_slab_alloc+0x12/0x20 kmem_cache_alloc+0x1c0/0x870 jffs2_alloc_xattr_ref+0x2f/0xa0 jffs2_scan_medium.cold+0x3713/0x4794 jffs2_do_mount_fs.cold+0xa7/0x2253 jffs2_do_fill_super+0x383/0xc30 jffs2_fill_super+0x2ea/0x4c0 [...] Liberado por la tarea 719: kmem_cache_free+0xcc/0x7b0 jffs2_free_xattr_ref+0x78/0x98 jffs2_clear_xattr_subsystem+0xa1/0x6ac jffs2_do_mount_fs.cold+0x5e6/0x2253 jffs2_do_fill_super+0x383/0xc30 jffs2_fill_super+0x2ea/0x4c0 [...] La direcci\u00f3n con errores pertenece al objeto en ffff8881243384b8 que pertenece al cach\u00e9 jffs2_xattr_ref de tama\u00f1o 48 La direcci\u00f3n con errores se encuentra 40 bytes dentro de la regi\u00f3n de 48 bytes [ffff8881243384b8, ffff8881243384e8) [...] ========================================================================== La activaci\u00f3n del ERROR se muestra en la siguiente pila: ----------------------------------------------------------- jffs2_fill_super jffs2_do_fill_super jffs2_do_mount_fs jffs2_build_filesystem jffs2_scan_medium jffs2_scan_eraseblock &lt;--- ERROR jffs2_clear_xattr_subsystem &lt;--- free jffs2_clear_xattr_subsystem &lt;--- free again ----------------------------------------------------------- Se devuelve un error en jffs2_do_mount_fs(). Si jffs2_sum_init() devuelve el error, no es necesario ejecutar jffs2_clear_xattr_subsystem(). Si jffs2_build_filesystem() devuelve el error, tampoco es necesario volver a ejecutar jffs2_clear_xattr_subsystem(). Por lo tanto, mueva jffs2_clear_xattr_subsystem() de 'out_inohash' a 'out_root' para solucionar este problema de UAF."}], "id": "CVE-2021-47656", "lastModified": "2025-03-24T17:45:55.750", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2025-02-26T06:37:07.360", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/22327bd7988f21de3a53c1373f3b81542bfe1f44"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/30bf7244acf32f19cb722c39f7bc1c2a9f300422"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/3bd2454162ec6bbb5503233c804fce6e4b6dcec5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/4c7c44ee1650677fbe89d86edbad9497b7679b5c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/7a75740206af5f17e9f3efa384211cba70213da1"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/7bb7428dd73991bf4b3a7a61b493ca50046c2b13"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/8c0f024f29e055840a5a89fe23b96ae3f921afed"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/9150cb625b46f68d524f4cfd491f1aafc23e10a9"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c3b07c875fa8f906f932976460fd14798596f101"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-416"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "kernel: jffs2: fix use-after-free in jffs2_clear_xattr_subsystem", "id": "2348186", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2348186"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "details": ["In the Linux kernel, the following vulnerability has been resolved:\njffs2: fix use-after-free in jffs2_clear_xattr_subsystem\nWhen we mount a jffs2 image, assume that the first few blocks of\nthe image are normal and contain at least one xattr-related inode,\nbut the next block is abnormal. As a result, an error is returned\nin jffs2_scan_eraseblock(). jffs2_clear_xattr_subsystem() is then\ncalled in jffs2_build_filesystem() and then again in\njffs2_do_fill_super().\nFinally we can observe the following report:\n==================================================================\nBUG: KASAN: use-after-free in jffs2_clear_xattr_subsystem+0x95/0x6ac\nRead of size 8 at addr ffff8881243384e0 by task mount/719\nCall Trace:\ndump_stack+0x115/0x16b\njffs2_clear_xattr_subsystem+0x95/0x6ac\njffs2_do_fill_super+0x84f/0xc30\njffs2_fill_super+0x2ea/0x4c0\nmtd_get_sb+0x254/0x400\nmtd_get_sb_by_nr+0x4f/0xd0\nget_tree_mtd+0x498/0x840\njffs2_get_tree+0x25/0x30\nvfs_get_tree+0x8d/0x2e0\npath_mount+0x50f/0x1e50\ndo_mount+0x107/0x130\n__se_sys_mount+0x1c5/0x2f0\n__x64_sys_mount+0xc7/0x160\ndo_syscall_64+0x45/0x70\nentry_SYSCALL_64_after_hwframe+0x44/0xa9\nAllocated by task 719:\nkasan_save_stack+0x23/0x60\n__kasan_kmalloc.constprop.0+0x10b/0x120\nkasan_slab_alloc+0x12/0x20\nkmem_cache_alloc+0x1c0/0x870\njffs2_alloc_xattr_ref+0x2f/0xa0\njffs2_scan_medium.cold+0x3713/0x4794\njffs2_do_mount_fs.cold+0xa7/0x2253\njffs2_do_fill_super+0x383/0xc30\njffs2_fill_super+0x2ea/0x4c0\n[...]\nFreed by task 719:\nkmem_cache_free+0xcc/0x7b0\njffs2_free_xattr_ref+0x78/0x98\njffs2_clear_xattr_subsystem+0xa1/0x6ac\njffs2_do_mount_fs.cold+0x5e6/0x2253\njffs2_do_fill_super+0x383/0xc30\njffs2_fill_super+0x2ea/0x4c0\n[...]\nThe buggy address belongs to the object at ffff8881243384b8\nwhich belongs to the cache jffs2_xattr_ref of size 48\nThe buggy address is located 40 bytes inside of\n48-byte region [ffff8881243384b8, ffff8881243384e8)\n[...]\n==================================================================\nThe triggering of the BUG is shown in the following stack:\n-----------------------------------------------------------\njffs2_fill_super\njffs2_do_fill_super\njffs2_do_mount_fs\njffs2_build_filesystem\njffs2_scan_medium\njffs2_scan_eraseblock <--- ERROR\njffs2_clear_xattr_subsystem <--- free\njffs2_clear_xattr_subsystem <--- free again\n-----------------------------------------------------------\nAn error is returned in jffs2_do_mount_fs(). If the error is returned\nby jffs2_sum_init(), the jffs2_clear_xattr_subsystem() does not need to\nbe executed. If the error is returned by jffs2_build_filesystem(), the\njffs2_clear_xattr_subsystem() also does not need to be executed again.\nSo move jffs2_clear_xattr_subsystem() from 'out_inohash' to 'out_root'\nto fix this UAF problem."], "name": "CVE-2021-47656", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-02-26T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-47656\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-47656\nhttps://lore.kernel.org/linux-cve-announce/2025022650-CVE-2021-47656-0abd@gregkh/T"], "threat_severity": "Moderate"}