CVE-2026-64593
Estado: RecibidaSin puntuar—
In the Linux kernel, the following vulnerability has been resolved:
btrfs: do not trim a device which is not writeable
[BUG] There is a bug report that btrfs/242 can randomly fail with the following NULL pointer dereference:
Also the reporter is very kind to test the following ASSERT() added to btrfs_trim_free_extents_throttle():
And it shows the following output:
Which means the device->bdev is NULL, and the dev_state is BTRFS_DEV_STATE_IN_FS_METADATA | BTRFS_DEV_STATE_ITEM_FOUND, without BTRFS_DEV_STATE_WRITEABLE flag set.
[CAUSE] The pc points to the following call chain:
So the NULL pointer dereference is caused by device->bdev being NULL.
Leer descripción completaMostrar menos
This looks impossible by a quick glance, as just before calling btrfs_trim_free_extents_throttle(), we have skipped any device that has BTRFS_DEV_STATE_MISSING flag set.
However in this particular case, there is a window where the missing device is later re-scanned, causing btrfs to remove the BTRFS_DEV_STATE_MISSING flag:
This allows the missing device to re-appear and clear the BTRFS_DEV_STATE_MISSING flag. However the device still does not have the BTRFS_DEV_STATE_WRITEABLE flag set, nor is its bdev pointer updated.
The bdev pointer remains NULL, triggering the crash later.
[FIX] This is a big de-synchronization between BTRFS_DEV_STATE_MISSING and device->bdev pointer, and shows a gap in btrfs's re-appearing-device handling.
The proper handling of re-appearing device will need quite some extra work, which is out of the context of this small ---truncated---
Detalles técnicos trazas, registros y código del informe original
run fstests btrfs/242 at 2026-06-01 10:25:08
BTRFS: device fsid d4d7f234-487c-4787-88e4-47a8b68c9874 devid 1 transid 9 /dev/sdc (8:32) scanned by mount (122609)
BTRFS info (device sdc): first mount of filesystem d4d7f234-487c-4787-88e4-47a8b68c9874
BTRFS info (device sdc): using crc32c checksum algorithm
BTRFS warning (device sdc): devid 2 uuid fbe72d72-3272-482d-80fb-ab88ed398192 is missing
BTRFS warning (device sdc): devid 2 uuid fbe72d72-3272-482d-80fb-ab88ed398192 is missing
BTRFS info (device sdc): allowing degraded mounts
BTRFS info (device sdc): turning on async discard
BTRFS info (device sdc): enabling free space tree
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018
user pgtable: 4k pages, 48-bit VAs, pgdp=000000013fd6b000
CPU: 4 UID: 0 PID: 122625 Comm: fstrim Not tainted 7.0.10-2-default #1 PREEMPT(full) openSUSE Tumbleweed e9a5f6b24978fba3bf015a992f865837fdfff3dd
Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20250812-19.fc42 08/12/2025
pstate: 01400005 (nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
pc : btrfs_trim_fs+0x34c/0xa00 [btrfs]
lr : btrfs_trim_fs+0x1f0/0xa00 [btrfs]
Call trace:
btrfs_trim_fs+0x34c/0xa00 [btrfs f02c1d570ceea621c69d302ba75dd61868083840] (P)
btrfs_ioctl_fitrim+0xe8/0x178 [btrfs f02c1d570ceea621c69d302ba75dd61868083840]
btrfs_ioctl+0xdd4/0x2bd8 [btrfs f02c1d570ceea621c69d302ba75dd61868083840]
__arm64_sys_ioctl+0xac/0x108
invoke_syscall.constprop.0+0x5c/0xd0
el0_svc_common.constprop.0+0x40/0xf0
do_el0_svc+0x24/0x40
el0_svc+0x40/0x1d0
el0t_64_sync_handler+0xa0/0xe8
el0t_64_sync+0x1b0/0x1b8
Code: 17ffff83 f94017e0 f9002be0 f9402ea0 (f9400c00)
---[ end trace 0000000000000000 ]---
ASSERT(device->bdev,
"devid=%llu path=%s dev_state=0x%lx\n",
device->devid, btrfs_dev_name(device), device->dev_state);
assertion failed: device->bdev, in extent-tree.c:6630 (devid=2 path=/dev/sdd dev_state=0x82)
btrfs_trim_fs()
|- btrfs_trim_free_extents()
|- btrfs_trim_free_extents_throttle()
|- bdev_max_discard_sectors(device->bdev)
btrfs_control_ioctl()
|- btrfs_scan_one_device()
|- device_list_add()
|- rcu_assign_pointer(device->name, name);
| This updates the missing device's path to the new good path.
|
|- clear_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)
This removes the BTRFS_DEV_STATE_MISSING flag.CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.17%
- Percentil entre todas las CVEs puntuadas: 5
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/02c903fc6fc7e16c5d1f22d18784f1208acf43e3
- https://git.kernel.org/stable/c/1b1937eb08f51319bf71575484cde2b8c517aedc
- https://git.kernel.org/stable/c/210af872eafa0cf572a84cb303c0f9d2914c1226
- https://git.kernel.org/stable/c/3d8fa4b828a86b33c60858e58aaab6df273ede05
- https://git.kernel.org/stable/c/7a64521802997257b144e6edfb4e278dbeb972dd
- https://git.kernel.org/stable/c/9c894159c5b8adc84072e3af0e55b0473a69564e
- https://git.kernel.org/stable/c/b4af31b898a948e29861cb0bae734058f9a49d9b
- https://git.kernel.org/stable/c/f41ae7e6664f3c4361129728f2c4d5f3ed995251
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-64593",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
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{
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"vendor": "Linux",
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{
"status": "unaffected",
"version": "0",
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{
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.212",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.96",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.39",
"versionType": "semver",
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},
{
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"versionType": "semver",
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},
{
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"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
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],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-08-06T08:16:34.730",
"references": [
{
"url": "https://git.kernel.org/stable/c/02c903fc6fc7e16c5d1f22d18784f1208acf43e3",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f41ae7e6664f3c4361129728f2c4d5f3ed995251",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"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---"
}
],
"lastModified": "2026-08-17T05:18:05.737",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}