dm ioctl: don't let data_start run past the buffer
Summary
| CVE | CVE-2026-99063 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-10-23 13:17:30 UTC |
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| Updated | 2026-10-23 13:17:30 UTC |
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| Description | In the Linux kernel, the following vulnerability has been resolved:
dm ioctl: don't let data_start run past the buffer
struct dm_ioctl has seven bytes of trailing padding, so the smallest
buffer userspace is allowed to ask for, offsetof(struct dm_ioctl, data),
is seven bytes shorter than sizeof(struct dm_ioctl).
get_result_buffer() sets data_start to sizeof(struct dm_ioctl) without
looking at how big the buffer actually is. Ask for the minimum and
data_start ends up seven bytes past the end. Callers add it to
data_size, and ctl_ioctl() copies that much back to userspace:
BUG: KASAN: slab-out-of-bounds in _copy_to_user+0xad/0xd0
Read of size 312 at addr ffff8880169e4c00 by task repro-dm/140
ctl_ioctl+0x5e3/0xcb0
dm_ctl_ioctl+0x25/0x40
allocated 305-byte region [ffff8880169e4c00, ffff8880169e4d31)
A DM_LIST_DEVICES with data_size set to 305 is enough to hit it, and the
seven bytes that leak are whatever sat next to the allocation.
Clamp data_start to the buffer size.
Note that this is not a security bug because the out-of-bounds read can
only be triggered by root. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 76c072b48e39e9291fbf02d6c912cf27d65e093d 98195e822343a656b92e235847ab3e72b1a3f920 git |
Not specified |
| CNA |
Linux |
Linux |
affected 76c072b48e39e9291fbf02d6c912cf27d65e093d e5c3f3d8935ecc64c962fb66e6a86dbf79218f61 git |
Not specified |
| CNA |
Linux |
Linux |
affected 76c072b48e39e9291fbf02d6c912cf27d65e093d 5680b6fb3054677d4ee65d3baba24b649f1b430e git |
Not specified |
| CNA |
Linux |
Linux |
affected 76c072b48e39e9291fbf02d6c912cf27d65e093d 725b49c689bbb29ef740b0d6b5ea9390baa9a695 git |
Not specified |
| CNA |
Linux |
Linux |
affected 76c072b48e39e9291fbf02d6c912cf27d65e093d 9b3fcf519d370df94a56f3b272d9eddffffa5be8 git |
Not specified |
| CNA |
Linux |
Linux |
affected 2.6.25 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 2.6.25 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.6.160 6.6.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.113 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.57 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2.11 7.2.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.3 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/9b3fcf519d370df94a56f3b272d9eddffffa5be8 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/5680b6fb3054677d4ee65d3baba24b649f1b430e |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/98195e822343a656b92e235847ab3e72b1a3f920 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/e5c3f3d8935ecc64c962fb66e6a86dbf79218f61 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/725b49c689bbb29ef740b0d6b5ea9390baa9a695 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.