{"id":"CVE-2026-64593","state":"PUBLISHED","title":"btrfs: do not trim a device which is not writeable","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not trim a device which is not writeable\n\n[BUG]\nThere is a bug report that btrfs/242 can randomly fail with the\nfollowing NULL pointer dereference:\n\n  run fstests btrfs/242 at 2026-06-01 10:25:08\n  BTRFS: device fsid d4d7f234-487c-4787-88e4-47a8b68c9874 devid 1 transid 9 /dev/sdc (8:32) scanned by mount (122609)\n  BTRFS info (device sdc): first mount of filesystem d4d7f234-487c-4787-88e4-47a8b68c9874\n  BTRFS info (device sdc): using crc32c checksum algorithm\n  BTRFS warning (device sdc): devid 2 uuid fbe72d72-3272-482d-80fb-ab88ed398192 is missing\n  BTRFS warning (device sdc): devid 2 uuid fbe72d72-3272-482d-80fb-ab88ed398192 is missing\n  BTRFS info (device sdc): allowing degraded mounts\n  BTRFS info (device sdc): turning on async discard\n  BTRFS info (device sdc): enabling free space tree\n  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018\n  user pgtable: 4k pages, 48-bit VAs, pgdp=000000013fd6b000\n  CPU: 4 UID: 0 PID: 122625 Comm: fstrim Not tainted 7.0.10-2-default #1 PREEMPT(full) openSUSE Tumbleweed e9a5f6b24978fba3bf015a992f865837fdfff3dd\n  Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20250812-19.fc42 08/12/2025\n  pstate: 01400005 (nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)\n  pc : btrfs_trim_fs+0x34c/0xa00 [btrfs]\n  lr : btrfs_trim_fs+0x1f0/0xa00 [btrfs]\n  Call trace:\n   btrfs_trim_fs+0x34c/0xa00 [btrfs f02c1d570ceea621c69d302ba75dd61868083840] (P)\n   btrfs_ioctl_fitrim+0xe8/0x178 [btrfs f02c1d570ceea621c69d302ba75dd61868083840]\n   btrfs_ioctl+0xdd4/0x2bd8 [btrfs f02c1d570ceea621c69d302ba75dd61868083840]\n   __arm64_sys_ioctl+0xac/0x108\n   invoke_syscall.constprop.0+0x5c/0xd0\n   el0_svc_common.constprop.0+0x40/0xf0\n   do_el0_svc+0x24/0x40\n   el0_svc+0x40/0x1d0\n   el0t_64_sync_handler+0xa0/0xe8\n   el0t_64_sync+0x1b0/0x1b8\n  Code: 17ffff83 f94017e0 f9002be0 f9402ea0 (f9400c00)\n  ---[ end trace 0000000000000000  ]---\n\nAlso the reporter is very kind to test the following ASSERT() added to\nbtrfs_trim_free_extents_throttle():\n\n\tASSERT(device->bdev,\n\t       \"devid=%llu path=%s dev_state=0x%lx\\n\",\n\t       device->devid, btrfs_dev_name(device), device->dev_state);\n\nAnd it shows the following output:\n\n  assertion failed: device->bdev, in extent-tree.c:6630 (devid=2 path=/dev/sdd dev_state=0x82)\n\nWhich means the device->bdev is NULL, and the dev_state is\nBTRFS_DEV_STATE_IN_FS_METADATA | BTRFS_DEV_STATE_ITEM_FOUND, without\nBTRFS_DEV_STATE_WRITEABLE flag set.\n\n[CAUSE]\nThe pc points to the following call chain:\n\n  btrfs_trim_fs()\n  |- btrfs_trim_free_extents()\n     |- btrfs_trim_free_extents_throttle()\n        |- bdev_max_discard_sectors(device->bdev)\n\nSo the NULL pointer dereference is caused by device->bdev being NULL.\n\nThis looks impossible by a quick glance, as just before calling\nbtrfs_trim_free_extents_throttle(), we have skipped any device that has\nBTRFS_DEV_STATE_MISSING flag set.\n\nHowever in this particular case, there is a window where the missing\ndevice is later re-scanned, causing btrfs to remove the\nBTRFS_DEV_STATE_MISSING flag:\n\n  btrfs_control_ioctl()\n  |- btrfs_scan_one_device()\n     |- device_list_add()\n        |- rcu_assign_pointer(device->name, name);\n        |  This updates the missing device's path to the new good path.\n        |\n        |- clear_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)\n           This removes the BTRFS_DEV_STATE_MISSING flag.\n\nThis allows the missing device to re-appear and clear the\nBTRFS_DEV_STATE_MISSING flag.  However the device still does not have\nthe BTRFS_DEV_STATE_WRITEABLE flag set, nor is its bdev pointer updated.\n\nThe bdev pointer remains NULL, triggering the crash later.\n\n[FIX]\nThis is a big de-synchronization between BTRFS_DEV_STATE_MISSING and\ndevice->bdev pointer, and shows a gap in btrfs's re-appearing-device\nhandling.\n\nThe proper handling of re-appearing device will need quite some extra\nwork, which is out of the context of this small\n---truncated---","publishedAt":"2026-08-06T07:13:49.700Z","updatedAt":"2026-08-17T04:58:15.319Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"f41ae7e6664f3c4361129728f2c4d5f3ed995251","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"210af872eafa0cf572a84cb303c0f9d2914c1226","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"3d8fa4b828a86b33c60858e58aaab6df273ede05","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"9c894159c5b8adc84072e3af0e55b0473a69564e","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"02c903fc6fc7e16c5d1f22d18784f1208acf43e3","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"7a64521802997257b144e6edfb4e278dbeb972dd","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"b4af31b898a948e29861cb0bae734058f9a49d9b","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"1b1937eb08f51319bf71575484cde2b8c517aedc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/extent-tree.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.3","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/extent-tree.c"]}],"references":["https://git.kernel.org/stable/c/f41ae7e6664f3c4361129728f2c4d5f3ed995251","https://git.kernel.org/stable/c/210af872eafa0cf572a84cb303c0f9d2914c1226","https://git.kernel.org/stable/c/3d8fa4b828a86b33c60858e58aaab6df273ede05","https://git.kernel.org/stable/c/9c894159c5b8adc84072e3af0e55b0473a69564e","https://git.kernel.org/stable/c/02c903fc6fc7e16c5d1f22d18784f1208acf43e3","https://git.kernel.org/stable/c/7a64521802997257b144e6edfb4e278dbeb972dd","https://git.kernel.org/stable/c/b4af31b898a948e29861cb0bae734058f9a49d9b","https://git.kernel.org/stable/c/1b1937eb08f51319bf71575484cde2b8c517aedc"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64593.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64593","state":"PUBLISHED","datePublished":"2026-08-06T07:13:49.700Z","dateUpdated":"2026-08-17T04:58:15.319Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.799Z"},"containers":{"cna":{"title":"btrfs: do not trim a device which is not writeable","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not trim a device which is not writeable\n\n[BUG]\nThere is a bug report that btrfs/242 can randomly fail with the\nfollowing NULL pointer dereference:\n\n  run fstests btrfs/242 at 2026-06-01 10:25:08\n  BTRFS: device fsid d4d7f234-487c-4787-88e4-47a8b68c9874 devid 1 transid 9 /dev/sdc (8:32) scanned by mount (122609)\n  BTRFS info (device sdc): first mount of filesystem d4d7f234-487c-4787-88e4-47a8b68c9874\n  BTRFS info (device sdc): using crc32c checksum algorithm\n  BTRFS warning (device sdc): devid 2 uuid fbe72d72-3272-482d-80fb-ab88ed398192 is missing\n  BTRFS warning (device sdc): devid 2 uuid fbe72d72-3272-482d-80fb-ab88ed398192 is missing\n  BTRFS info (device sdc): allowing degraded mounts\n  BTRFS info (device sdc): turning on async discard\n  BTRFS info (device sdc): enabling free space tree\n  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018\n  user pgtable: 4k pages, 48-bit VAs, pgdp=000000013fd6b000\n  CPU: 4 UID: 0 PID: 122625 Comm: fstrim Not tainted 7.0.10-2-default #1 PREEMPT(full) openSUSE Tumbleweed e9a5f6b24978fba3bf015a992f865837fdfff3dd\n  Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20250812-19.fc42 08/12/2025\n  pstate: 01400005 (nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)\n  pc : btrfs_trim_fs+0x34c/0xa00 [btrfs]\n  lr : btrfs_trim_fs+0x1f0/0xa00 [btrfs]\n  Call trace:\n   btrfs_trim_fs+0x34c/0xa00 [btrfs f02c1d570ceea621c69d302ba75dd61868083840] (P)\n   btrfs_ioctl_fitrim+0xe8/0x178 [btrfs f02c1d570ceea621c69d302ba75dd61868083840]\n   btrfs_ioctl+0xdd4/0x2bd8 [btrfs f02c1d570ceea621c69d302ba75dd61868083840]\n   __arm64_sys_ioctl+0xac/0x108\n   invoke_syscall.constprop.0+0x5c/0xd0\n   el0_svc_common.constprop.0+0x40/0xf0\n   do_el0_svc+0x24/0x40\n   el0_svc+0x40/0x1d0\n   el0t_64_sync_handler+0xa0/0xe8\n   el0t_64_sync+0x1b0/0x1b8\n  Code: 17ffff83 f94017e0 f9002be0 f9402ea0 (f9400c00)\n  ---[ end trace 0000000000000000  ]---\n\nAlso the reporter is very kind to test the following ASSERT() added to\nbtrfs_trim_free_extents_throttle():\n\n\tASSERT(device->bdev,\n\t       \"devid=%llu path=%s dev_state=0x%lx\\n\",\n\t       device->devid, btrfs_dev_name(device), device->dev_state);\n\nAnd it shows the following output:\n\n  assertion failed: device->bdev, in extent-tree.c:6630 (devid=2 path=/dev/sdd dev_state=0x82)\n\nWhich means the device->bdev is NULL, and the dev_state is\nBTRFS_DEV_STATE_IN_FS_METADATA | BTRFS_DEV_STATE_ITEM_FOUND, without\nBTRFS_DEV_STATE_WRITEABLE flag set.\n\n[CAUSE]\nThe pc points to the following call chain:\n\n  btrfs_trim_fs()\n  |- btrfs_trim_free_extents()\n     |- btrfs_trim_free_extents_throttle()\n        |- bdev_max_discard_sectors(device->bdev)\n\nSo the NULL pointer dereference is caused by device->bdev being NULL.\n\nThis looks impossible by a quick glance, as just before calling\nbtrfs_trim_free_extents_throttle(), we have skipped any device that has\nBTRFS_DEV_STATE_MISSING flag set.\n\nHowever in this particular case, there is a window where the missing\ndevice is later re-scanned, causing btrfs to remove the\nBTRFS_DEV_STATE_MISSING flag:\n\n  btrfs_control_ioctl()\n  |- btrfs_scan_one_device()\n     |- device_list_add()\n        |- rcu_assign_pointer(device->name, name);\n        |  This updates the missing device's path to the new good path.\n        |\n        |- clear_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)\n           This removes the BTRFS_DEV_STATE_MISSING flag.\n\nThis allows the missing device to re-appear and clear the\nBTRFS_DEV_STATE_MISSING flag.  However the device still does not have\nthe BTRFS_DEV_STATE_WRITEABLE flag set, nor is its bdev pointer updated.\n\nThe bdev pointer remains NULL, triggering the crash later.\n\n[FIX]\nThis is a big de-synchronization between BTRFS_DEV_STATE_MISSING and\ndevice->bdev pointer, and shows a gap in btrfs's re-appearing-device\nhandling.\n\nThe proper handling of re-appearing device will need quite some extra\nwork, which is out of the context of this small\n---truncated---"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"f41ae7e6664f3c4361129728f2c4d5f3ed995251","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"210af872eafa0cf572a84cb303c0f9d2914c1226","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"3d8fa4b828a86b33c60858e58aaab6df273ede05","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"9c894159c5b8adc84072e3af0e55b0473a69564e","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"02c903fc6fc7e16c5d1f22d18784f1208acf43e3","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"7a64521802997257b144e6edfb4e278dbeb972dd","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"b4af31b898a948e29861cb0bae734058f9a49d9b","versionType":"git"},{"version":"499f377f49f085ee4aa214c738e948e88626f39b","status":"affected","lessThan":"1b1937eb08f51319bf71575484cde2b8c517aedc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/extent-tree.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.3","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/extent-tree.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f41ae7e6664f3c4361129728f2c4d5f3ed995251"},{"url":"https://git.kernel.org/stable/c/210af872eafa0cf572a84cb303c0f9d2914c1226"},{"url":"https://git.kernel.org/stable/c/3d8fa4b828a86b33c60858e58aaab6df273ede05"},{"url":"https://git.kernel.org/stable/c/9c894159c5b8adc84072e3af0e55b0473a69564e"},{"url":"https://git.kernel.org/stable/c/02c903fc6fc7e16c5d1f22d18784f1208acf43e3"},{"url":"https://git.kernel.org/stable/c/7a64521802997257b144e6edfb4e278dbeb972dd"},{"url":"https://git.kernel.org/stable/c/b4af31b898a948e29861cb0bae734058f9a49d9b"},{"url":"https://git.kernel.org/stable/c/1b1937eb08f51319bf71575484cde2b8c517aedc"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:58:15.319Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.3","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.3","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.3","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.3","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.3","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.3","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.3","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.3","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}