{"id":"CVE-2021-47335","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to avoid racing on fsync_entry_slab by multi filesystem instances\n\nAs syzbot reported, there is an use-after-free issue during f2fs recovery:\n\nUse-after-free …","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to avoid racing on fsync_entry_slab by multi filesystem instances\n\nAs syzbot reported, there is an use-after-free issue during f2fs recovery:\n\nUse-after-free …","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel < 5.10.51","linux_kernel >= 5.11, < 5.12.18","linux_kernel >= 5.13, < 5.13.3"],"patched":["linux_kernel 5.13.3"],"published":"2024-05-21","updated":"2026-08-11","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-47335","references":[{"url":"https://git.kernel.org/stable/c/79fa5d944c875711253a23b8155b36883c696409","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/86786603014e0a22d0d6af8e80ae4b8687927048","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cad83c968c2ebe97905f900326988ed37146c347","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e472b276a0d2180808009be38105e12754432e2a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/79fa5d944c875711253a23b8155b36883c696409","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/86786603014e0a22d0d6af8e80ae4b8687927048","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/cad83c968c2ebe97905f900326988ed37146c347","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/e472b276a0d2180808009be38105e12754432e2a","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-47335.json"},{"url":"https://access.redhat.com/security/cve/CVE-2021-47335"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2282425"},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-47335"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-47335"}],"tags":["nvd","csaf","vex","red-hat"],"epss":0.00232,"epssPercentile":0.14349,"ingestedAt":"2026-08-11T16:47:02.972Z","scores":{"nvd":5.5,"vendor":6.3},"slug":"CVE-2021-47335","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to avoid racing on fsync_entry_slab by multi filesystem instances\n\nAs syzbot reported, there is an use-after-free issue during f2fs recovery:\n\nUse-after-free write at 0xffff88823bc16040 (in kfence-#10):\n kmem_cache_destroy+0x1f/0x120 mm/slab_common.c:486\n f2fs_recover_fsync_data+0x75b0/0x8380 fs/f2fs/recovery.c:869\n f2fs_fill_super+0x9393/0xa420 fs/f2fs/super.c:3945\n mount_bdev+0x26c/0x3a0 fs/super.c:1367\n legacy_get_tree+0xea/0x180 fs/fs_context.c:592\n vfs_get_tree+0x86/0x270 fs/super.c:1497\n do_new_mount fs/namespace.c:2905 [inline]\n path_mount+0x196f/0x2be0 fs/namespace.c:3235\n do_mount fs/namespace.c:3248 [inline]\n __do_sys_mount fs/namespace.c:3456 [inline]\n __se_sys_mount+0x2f9/0x3b0 fs/namespace.c:3433\n do_syscall_64+0x3f/0xb0 arch/x86/entry/common.c:47\n entry_SYSCALL_64_after_hwframe+0x44/0xae\n\nThe root cause is multi f2fs filesystem instances can race on accessing\nglobal fsync_entry_slab pointer, result in use-after-free issue of slab\ncache, fixes to init/destroy this slab cache only once during module\ninit/destroy procedure to avoid this issue.\n\n## Affected\n\n- `linux_kernel < 5.10.51`\n- `linux_kernel >= 5.11, < 5.12.18`\n- `linux_kernel >= 5.13, < 5.13.3`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 5.13.3`\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 · updated 2026-09-13 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-47335.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}