{"id":"CVE-2026-43299","state":"PUBLISHED","title":"btrfs: do not ASSERT() when the fs flips RO inside btrfs_repair_io_failure()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not ASSERT() when the fs flips RO inside btrfs_repair_io_failure()\n\n[BUG]\nThere is a bug report that when btrfs hits ENOSPC error in a critical\npath, btrfs flips RO (this part is expected, although the ENOSPC bug\nstill needs to be addressed).\n\nThe problem is after the RO flip, if there is a read repair pending, we\ncan hit the ASSERT() inside btrfs_repair_io_failure() like the following:\n\n  BTRFS info (device vdc): relocating block group 30408704 flags metadata|raid1\n  ------------[ cut here ]------------\n  BTRFS: Transaction aborted (error -28)\n  WARNING: fs/btrfs/extent-tree.c:3235 at __btrfs_free_extent.isra.0+0x453/0xfd0, CPU#1: btrfs/383844\n  Modules linked in: kvm_intel kvm irqbypass\n  [...]\n  ---[ end trace 0000000000000000 ]---\n  BTRFS info (device vdc state EA): 2 enospc errors during balance\n  BTRFS info (device vdc state EA): balance: ended with status: -30\n  BTRFS error (device vdc state EA): parent transid verify failed on logical 30556160 mirror 2 wanted 8 found 6\n  BTRFS error (device vdc state EA): bdev /dev/nvme0n1 errs: wr 0, rd 0, flush 0, corrupt 10, gen 0\n  [...]\n  assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938\n  ------------[ cut here ]------------\n  assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938\n  kernel BUG at fs/btrfs/bio.c:938!\n  Oops: invalid opcode: 0000 [#1] SMP NOPTI\n  CPU: 0 UID: 0 PID: 868 Comm: kworker/u8:13 Tainted: G        W        N  6.19.0-rc6+ #4788 PREEMPT(full)\n  Tainted: [W]=WARN, [N]=TEST\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\n  Workqueue: btrfs-endio simple_end_io_work\n  RIP: 0010:btrfs_repair_io_failure.cold+0xb2/0x120\n  RSP: 0000:ffffc90001d2bcf0 EFLAGS: 00010246\n  RAX: 0000000000000051 RBX: 0000000000001000 RCX: 0000000000000000\n  RDX: 0000000000000000 RSI: ffffffff8305cf42 RDI: 00000000ffffffff\n  RBP: 0000000000000002 R08: 00000000fffeffff R09: ffffffff837fa988\n  R10: ffffffff8327a9e0 R11: 6f69747265737361 R12: ffff88813018d310\n  R13: ffff888168b8a000 R14: ffffc90001d2bd90 R15: ffff88810a169000\n  FS:  0000000000000000(0000) GS:ffff8885e752c000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  ------------[ cut here ]------------\n\n[CAUSE]\nThe cause of -ENOSPC error during the test case btrfs/124 is still\nunknown, although it's known that we still have cases where metadata can\nbe over-committed but can not be fulfilled correctly, thus if we hit\nsuch ENOSPC error inside a critical path, we have no choice but abort\nthe current transaction.\n\nThis will mark the fs read-only.\n\nThe problem is inside the btrfs_repair_io_failure() path that we require\nthe fs not to be mount read-only. This is normally fine, but if we are\ndoing a read-repair meanwhile the fs flips RO due to a critical error,\nwe can enter btrfs_repair_io_failure() with super block set to\nread-only, thus triggering the above crash.\n\n[FIX]\nJust replace the ASSERT() with a proper return if the fs is already\nread-only.","publishedAt":"2026-05-08T13:11:20.872Z","updatedAt":"2026-10-30T12:25:23.043Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"053dd7f3c9647d3a781919c1b14105f46786d677","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"a35b38cb4b0dd08d7cc0bd4e400208c7aeba8a72","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"da3f596073de1c3cbc99941f01296968a85c8c76","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"81e1ae665004b99a10686473d99f0a7cb6335f38","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"f6df18c001e3dcebc08482d0adeacd0cfea08593","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"8ceaad6cd6e7fa5f73b0b2796a2e85d75d37e9f3","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/bio.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.13","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/bio.c"]}],"references":["https://git.kernel.org/stable/c/053dd7f3c9647d3a781919c1b14105f46786d677","https://git.kernel.org/stable/c/a35b38cb4b0dd08d7cc0bd4e400208c7aeba8a72","https://git.kernel.org/stable/c/da3f596073de1c3cbc99941f01296968a85c8c76","https://git.kernel.org/stable/c/81e1ae665004b99a10686473d99f0a7cb6335f38","https://git.kernel.org/stable/c/f6df18c001e3dcebc08482d0adeacd0cfea08593","https://git.kernel.org/stable/c/8ceaad6cd6e7fa5f73b0b2796a2e85d75d37e9f3"],"weaknesses":[],"ingestedAt":"2026-10-30T12:42:04.495Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43299.json","commit":"db8103c5921aac81d5d90efcf3745980dafabf49","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43299","state":"PUBLISHED","datePublished":"2026-05-08T13:11:20.872Z","dateUpdated":"2026-10-30T12:25:23.043Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:56.000Z"},"containers":{"cna":{"title":"btrfs: do not ASSERT() when the fs flips RO inside btrfs_repair_io_failure()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not ASSERT() when the fs flips RO inside btrfs_repair_io_failure()\n\n[BUG]\nThere is a bug report that when btrfs hits ENOSPC error in a critical\npath, btrfs flips RO (this part is expected, although the ENOSPC bug\nstill needs to be addressed).\n\nThe problem is after the RO flip, if there is a read repair pending, we\ncan hit the ASSERT() inside btrfs_repair_io_failure() like the following:\n\n  BTRFS info (device vdc): relocating block group 30408704 flags metadata|raid1\n  ------------[ cut here ]------------\n  BTRFS: Transaction aborted (error -28)\n  WARNING: fs/btrfs/extent-tree.c:3235 at __btrfs_free_extent.isra.0+0x453/0xfd0, CPU#1: btrfs/383844\n  Modules linked in: kvm_intel kvm irqbypass\n  [...]\n  ---[ end trace 0000000000000000 ]---\n  BTRFS info (device vdc state EA): 2 enospc errors during balance\n  BTRFS info (device vdc state EA): balance: ended with status: -30\n  BTRFS error (device vdc state EA): parent transid verify failed on logical 30556160 mirror 2 wanted 8 found 6\n  BTRFS error (device vdc state EA): bdev /dev/nvme0n1 errs: wr 0, rd 0, flush 0, corrupt 10, gen 0\n  [...]\n  assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938\n  ------------[ cut here ]------------\n  assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938\n  kernel BUG at fs/btrfs/bio.c:938!\n  Oops: invalid opcode: 0000 [#1] SMP NOPTI\n  CPU: 0 UID: 0 PID: 868 Comm: kworker/u8:13 Tainted: G        W        N  6.19.0-rc6+ #4788 PREEMPT(full)\n  Tainted: [W]=WARN, [N]=TEST\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\n  Workqueue: btrfs-endio simple_end_io_work\n  RIP: 0010:btrfs_repair_io_failure.cold+0xb2/0x120\n  RSP: 0000:ffffc90001d2bcf0 EFLAGS: 00010246\n  RAX: 0000000000000051 RBX: 0000000000001000 RCX: 0000000000000000\n  RDX: 0000000000000000 RSI: ffffffff8305cf42 RDI: 00000000ffffffff\n  RBP: 0000000000000002 R08: 00000000fffeffff R09: ffffffff837fa988\n  R10: ffffffff8327a9e0 R11: 6f69747265737361 R12: ffff88813018d310\n  R13: ffff888168b8a000 R14: ffffc90001d2bd90 R15: ffff88810a169000\n  FS:  0000000000000000(0000) GS:ffff8885e752c000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  ------------[ cut here ]------------\n\n[CAUSE]\nThe cause of -ENOSPC error during the test case btrfs/124 is still\nunknown, although it's known that we still have cases where metadata can\nbe over-committed but can not be fulfilled correctly, thus if we hit\nsuch ENOSPC error inside a critical path, we have no choice but abort\nthe current transaction.\n\nThis will mark the fs read-only.\n\nThe problem is inside the btrfs_repair_io_failure() path that we require\nthe fs not to be mount read-only. This is normally fine, but if we are\ndoing a read-repair meanwhile the fs flips RO due to a critical error,\nwe can enter btrfs_repair_io_failure() with super block set to\nread-only, thus triggering the above crash.\n\n[FIX]\nJust replace the ASSERT() with a proper return if the fs is already\nread-only."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"053dd7f3c9647d3a781919c1b14105f46786d677","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"a35b38cb4b0dd08d7cc0bd4e400208c7aeba8a72","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"da3f596073de1c3cbc99941f01296968a85c8c76","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"81e1ae665004b99a10686473d99f0a7cb6335f38","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"f6df18c001e3dcebc08482d0adeacd0cfea08593","versionType":"git"},{"version":"908960c6c0fb3b3ce3971dc0ca47b581d256b968","status":"affected","lessThan":"8ceaad6cd6e7fa5f73b0b2796a2e85d75d37e9f3","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/bio.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.13","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/bio.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/053dd7f3c9647d3a781919c1b14105f46786d677"},{"url":"https://git.kernel.org/stable/c/a35b38cb4b0dd08d7cc0bd4e400208c7aeba8a72"},{"url":"https://git.kernel.org/stable/c/da3f596073de1c3cbc99941f01296968a85c8c76"},{"url":"https://git.kernel.org/stable/c/81e1ae665004b99a10686473d99f0a7cb6335f38"},{"url":"https://git.kernel.org/stable/c/f6df18c001e3dcebc08482d0adeacd0cfea08593"},{"url":"https://git.kernel.org/stable/c/8ceaad6cd6e7fa5f73b0b2796a2e85d75d37e9f3"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:25:23.043Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.13","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.13","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.13","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.13","versionEndExcluding":"6.18.57"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.13","versionEndExcluding":"6.19.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.13","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}