{"api_version":"1","generated_at":"2026-08-24T10:33:21+00:00","cve":"CVE-2021-47335","urls":{"html":"https://cve.report/CVE-2021-47335","api":"https://cve.report/api/cve/CVE-2021-47335.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2021-47335","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-47335"},"summary":{"title":"f2fs: fix to avoid racing on fsync_entry_slab by multi filesystem instances","description":"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 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.","state":"PUBLISHED","assigner":"Linux","published_at":"2024-05-21 15:15:20","updated_at":"2026-08-11 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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 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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.","Type":"Description","Title":"f2fs: fix to avoid racing on fsync_entry_slab by multi filesyste"}]}}}