{"api_version":"1","generated_at":"2026-08-22T23:25:02+00:00","cve":"CVE-2021-46958","urls":{"html":"https://cve.report/CVE-2021-46958","api":"https://cve.report/api/cve/CVE-2021-46958.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2021-46958","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-46958"},"summary":{"title":"btrfs: fix race between transaction aborts and fsyncs leading to use-after-free","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix race between transaction aborts and fsyncs leading to use-after-free\n\nThere is a race between a task aborting a transaction during a commit,\na task doing an fsync and the transaction kthread, which leads to an\nuse-after-free of the log root tree. When this happens, it results in a\nstack trace like the following:\n\n  BTRFS info (device dm-0): forced readonly\n  BTRFS warning (device dm-0): Skipping commit of aborted transaction.\n  BTRFS: error (device dm-0) in cleanup_transaction:1958: errno=-5 IO failure\n  BTRFS warning (device dm-0): lost page write due to IO error on /dev/mapper/error-test (-5)\n  BTRFS warning (device dm-0): Skipping commit of aborted transaction.\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0xa4e8 len 4096 err no 10\n  BTRFS error (device dm-0): error writing primary super block to device 1\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e000 len 4096 err no 10\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e008 len 4096 err no 10\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e010 len 4096 err no 10\n  BTRFS: error (device dm-0) in write_all_supers:4110: errno=-5 IO failure (1 errors while writing supers)\n  BTRFS: error (device dm-0) in btrfs_sync_log:3308: errno=-5 IO failure\n  general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b68: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI\n  CPU: 2 PID: 2458471 Comm: fsstress Not tainted 5.12.0-rc5-btrfs-next-84 #1\n  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014\n  RIP: 0010:__mutex_lock+0x139/0xa40\n  Code: c0 74 19 (...)\n  RSP: 0018:ffff9f18830d7b00 EFLAGS: 00010202\n  RAX: 6b6b6b6b6b6b6b68 RBX: 0000000000000001 RCX: 0000000000000002\n  RDX: ffffffffb9c54d13 RSI: 0000000000000000 RDI: 0000000000000000\n  RBP: ffff9f18830d7bc0 R08: 0000000000000000 R09: 0000000000000000\n  R10: ffff9f18830d7be0 R11: 0000000000000001 R12: ffff8c6cd199c040\n  R13: ffff8c6c95821358 R14: 00000000fffffffb R15: ffff8c6cbcf01358\n  FS:  00007fa9140c2b80(0000) GS:ffff8c6fac600000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00007fa913d52000 CR3: 000000013d2b4003 CR4: 0000000000370ee0\n  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n  Call Trace:\n   ? __btrfs_handle_fs_error+0xde/0x146 [btrfs]\n   ? btrfs_sync_log+0x7c1/0xf20 [btrfs]\n   ? btrfs_sync_log+0x7c1/0xf20 [btrfs]\n   btrfs_sync_log+0x7c1/0xf20 [btrfs]\n   btrfs_sync_file+0x40c/0x580 [btrfs]\n   do_fsync+0x38/0x70\n   __x64_sys_fsync+0x10/0x20\n   do_syscall_64+0x33/0x80\n   entry_SYSCALL_64_after_hwframe+0x44/0xae\n  RIP: 0033:0x7fa9142a55c3\n  Code: 8b 15 09 (...)\n  RSP: 002b:00007fff26278d48 EFLAGS: 00000246 ORIG_RAX: 000000000000004a\n  RAX: ffffffffffffffda RBX: 0000563c83cb4560 RCX: 00007fa9142a55c3\n  RDX: 00007fff26278cb0 RSI: 00007fff26278cb0 RDI: 0000000000000005\n  RBP: 0000000000000005 R08: 0000000000000001 R09: 00007fff26278d5c\n  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000340\n  R13: 00007fff26278de0 R14: 00007fff26278d96 R15: 0000563c83ca57c0\n  Modules linked in: btrfs dm_zero dm_snapshot dm_thin_pool (...)\n  ---[ end trace ee2f1b19327d791d ]---\n\nThe steps that lead to this crash are the following:\n\n1) We are at transaction N;\n\n2) We have two tasks with a transaction handle attached to transaction N.\n   Task A and Task B. Task B is doing an fsync;\n\n3) Task B is at btrfs_sync_log(), and has saved fs_info->log_root_tree\n   into a local variable named 'log_root_tree' at the top of\n   btrfs_sync_log(). Task B is about to call write_all_supers(), but\n   before that...\n\n4) Task A calls btrfs_commit_transaction(), and after it sets the\n   transaction state to TRANS_STATE_COMMIT_START, an error happens before\n   it w\n---truncated---","state":"PUBLISHED","assigner":"Linux","published_at":"2024-02-27 19:04:06","updated_at":"2026-08-04 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the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix race between transaction aborts and fsyncs leading to use-after-free\n\nThere is a race between a task aborting a transaction during a commit,\na task doing an fsync and the transaction kthread, which leads to an\nuse-after-free of the log root tree. When this happens, it results in a\nstack trace like the following:\n\n  BTRFS info (device dm-0): forced readonly\n  BTRFS warning (device dm-0): Skipping commit of aborted transaction.\n  BTRFS: error (device dm-0) in cleanup_transaction:1958: errno=-5 IO failure\n  BTRFS warning (device dm-0): lost page write due to IO error on /dev/mapper/error-test (-5)\n  BTRFS warning (device dm-0): Skipping commit of aborted transaction.\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0xa4e8 len 4096 err no 10\n  BTRFS error (device dm-0): error writing primary super block to device 1\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e000 len 4096 err no 10\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e008 len 4096 err no 10\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e010 len 4096 err no 10\n  BTRFS: error (device dm-0) in write_all_supers:4110: errno=-5 IO failure (1 errors while writing supers)\n  BTRFS: error (device dm-0) in btrfs_sync_log:3308: errno=-5 IO failure\n  general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b68: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI\n  CPU: 2 PID: 2458471 Comm: fsstress Not tainted 5.12.0-rc5-btrfs-next-84 #1\n  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014\n  RIP: 0010:__mutex_lock+0x139/0xa40\n  Code: c0 74 19 (...)\n  RSP: 0018:ffff9f18830d7b00 EFLAGS: 00010202\n  RAX: 6b6b6b6b6b6b6b68 RBX: 0000000000000001 RCX: 0000000000000002\n  RDX: ffffffffb9c54d13 RSI: 0000000000000000 RDI: 0000000000000000\n  RBP: ffff9f18830d7bc0 R08: 0000000000000000 R09: 0000000000000000\n  R10: ffff9f18830d7be0 R11: 0000000000000001 R12: ffff8c6cd199c040\n  R13: ffff8c6c95821358 R14: 00000000fffffffb R15: ffff8c6cbcf01358\n  FS:  00007fa9140c2b80(0000) GS:ffff8c6fac600000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00007fa913d52000 CR3: 000000013d2b4003 CR4: 0000000000370ee0\n  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n  Call Trace:\n   ? __btrfs_handle_fs_error+0xde/0x146 [btrfs]\n   ? btrfs_sync_log+0x7c1/0xf20 [btrfs]\n   ? btrfs_sync_log+0x7c1/0xf20 [btrfs]\n   btrfs_sync_log+0x7c1/0xf20 [btrfs]\n   btrfs_sync_file+0x40c/0x580 [btrfs]\n   do_fsync+0x38/0x70\n   __x64_sys_fsync+0x10/0x20\n   do_syscall_64+0x33/0x80\n   entry_SYSCALL_64_after_hwframe+0x44/0xae\n  RIP: 0033:0x7fa9142a55c3\n  Code: 8b 15 09 (...)\n  RSP: 002b:00007fff26278d48 EFLAGS: 00000246 ORIG_RAX: 000000000000004a\n  RAX: ffffffffffffffda RBX: 0000563c83cb4560 RCX: 00007fa9142a55c3\n  RDX: 00007fff26278cb0 RSI: 00007fff26278cb0 RDI: 0000000000000005\n  RBP: 0000000000000005 R08: 0000000000000001 R09: 00007fff26278d5c\n  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000340\n  R13: 00007fff26278de0 R14: 00007fff26278d96 R15: 0000563c83ca57c0\n  Modules linked in: btrfs dm_zero dm_snapshot dm_thin_pool (...)\n  ---[ end trace ee2f1b19327d791d ]---\n\nThe steps that lead to this crash are the following:\n\n1) We are at transaction N;\n\n2) We have two tasks with a transaction handle attached to transaction N.\n   Task A and Task B. Task B is doing an fsync;\n\n3) Task B is at btrfs_sync_log(), and has saved fs_info->log_root_tree\n   into a local variable named 'log_root_tree' at the top of\n   btrfs_sync_log(). Task B is about to call write_all_supers(), but\n   before that...\n\n4) Task A calls btrfs_commit_transaction(), and after it sets the\n   transaction state to TRANS_STATE_COMMIT_START, an error happens before\n   it w\n---truncated---"}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-08-04T08:57:58.294Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a4794be7b00b7eda4b45fffd283ab7d76df7e5d6"},{"url":"https://git.kernel.org/stable/c/633f7f216663587f17601eaa1cf2ac3d5654874c"},{"url":"https://git.kernel.org/stable/c/e2da98788369bfba1138bada72765c47989a4338"},{"url":"https://git.kernel.org/stable/c/061dde8245356d8864d29e25207aa4daa0be4d3c"}],"title":"btrfs: fix race between transaction aborts and fsyncs leading to use-after-free","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2021-46958","datePublished":"2024-02-27T18:46:59.315Z","dateReserved":"2024-02-27T18:42:55.939Z","dateUpdated":"2026-08-04T08:57:58.294Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2024-02-27 19:04:06","lastModifiedDate":"2026-08-04 10:16:38","problem_types":["CWE-416"],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9},{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":4.7,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1,"impactScore":3.6}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2024-08-15T19:27:46.078537Z","id":"CVE-2021-46958","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.10.36","matchCriteriaId":"C6E35DB7-8D08-44A4-88FE-9B73324500C3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.11.20","matchCriteriaId":"EEC03413-9760-46D4-AC1D-EB084A1D4111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"5.12.3","matchCriteriaId":"F9D6B2DE-7E4A-4B3B-9AEE-3A2C5F23DA32"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2021","CveId":"46958","Ordinal":"1","Title":"btrfs: fix race between transaction aborts and fsyncs leading to","CVE":"CVE-2021-46958","Year":"2021"},"notes":[{"CveYear":"2021","CveId":"46958","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix race between transaction aborts and fsyncs leading to use-after-free\n\nThere is a race between a task aborting a transaction during a commit,\na task doing an fsync and the transaction kthread, which leads to an\nuse-after-free of the log root tree. When this happens, it results in a\nstack trace like the following:\n\n  BTRFS info (device dm-0): forced readonly\n  BTRFS warning (device dm-0): Skipping commit of aborted transaction.\n  BTRFS: error (device dm-0) in cleanup_transaction:1958: errno=-5 IO failure\n  BTRFS warning (device dm-0): lost page write due to IO error on /dev/mapper/error-test (-5)\n  BTRFS warning (device dm-0): Skipping commit of aborted transaction.\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0xa4e8 len 4096 err no 10\n  BTRFS error (device dm-0): error writing primary super block to device 1\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e000 len 4096 err no 10\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e008 len 4096 err no 10\n  BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e010 len 4096 err no 10\n  BTRFS: error (device dm-0) in write_all_supers:4110: errno=-5 IO failure (1 errors while writing supers)\n  BTRFS: error (device dm-0) in btrfs_sync_log:3308: errno=-5 IO failure\n  general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b68: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI\n  CPU: 2 PID: 2458471 Comm: fsstress Not tainted 5.12.0-rc5-btrfs-next-84 #1\n  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014\n  RIP: 0010:__mutex_lock+0x139/0xa40\n  Code: c0 74 19 (...)\n  RSP: 0018:ffff9f18830d7b00 EFLAGS: 00010202\n  RAX: 6b6b6b6b6b6b6b68 RBX: 0000000000000001 RCX: 0000000000000002\n  RDX: ffffffffb9c54d13 RSI: 0000000000000000 RDI: 0000000000000000\n  RBP: ffff9f18830d7bc0 R08: 0000000000000000 R09: 0000000000000000\n  R10: ffff9f18830d7be0 R11: 0000000000000001 R12: ffff8c6cd199c040\n  R13: ffff8c6c95821358 R14: 00000000fffffffb R15: ffff8c6cbcf01358\n  FS:  00007fa9140c2b80(0000) GS:ffff8c6fac600000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00007fa913d52000 CR3: 000000013d2b4003 CR4: 0000000000370ee0\n  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n  Call Trace:\n   ? __btrfs_handle_fs_error+0xde/0x146 [btrfs]\n   ? btrfs_sync_log+0x7c1/0xf20 [btrfs]\n   ? btrfs_sync_log+0x7c1/0xf20 [btrfs]\n   btrfs_sync_log+0x7c1/0xf20 [btrfs]\n   btrfs_sync_file+0x40c/0x580 [btrfs]\n   do_fsync+0x38/0x70\n   __x64_sys_fsync+0x10/0x20\n   do_syscall_64+0x33/0x80\n   entry_SYSCALL_64_after_hwframe+0x44/0xae\n  RIP: 0033:0x7fa9142a55c3\n  Code: 8b 15 09 (...)\n  RSP: 002b:00007fff26278d48 EFLAGS: 00000246 ORIG_RAX: 000000000000004a\n  RAX: ffffffffffffffda RBX: 0000563c83cb4560 RCX: 00007fa9142a55c3\n  RDX: 00007fff26278cb0 RSI: 00007fff26278cb0 RDI: 0000000000000005\n  RBP: 0000000000000005 R08: 0000000000000001 R09: 00007fff26278d5c\n  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000340\n  R13: 00007fff26278de0 R14: 00007fff26278d96 R15: 0000563c83ca57c0\n  Modules linked in: btrfs dm_zero dm_snapshot dm_thin_pool (...)\n  ---[ end trace ee2f1b19327d791d ]---\n\nThe steps that lead to this crash are the following:\n\n1) We are at transaction N;\n\n2) We have two tasks with a transaction handle attached to transaction N.\n   Task A and Task B. Task B is doing an fsync;\n\n3) Task B is at btrfs_sync_log(), and has saved fs_info->log_root_tree\n   into a local variable named 'log_root_tree' at the top of\n   btrfs_sync_log(). Task B is about to call write_all_supers(), but\n   before that...\n\n4) Task A calls btrfs_commit_transaction(), and after it sets the\n   transaction state to TRANS_STATE_COMMIT_START, an error happens before\n   it w\n---truncated---","Type":"Description","Title":"btrfs: fix race between transaction aborts and fsyncs leading to"}]}}}