dcache: don't put a mountpoint on a dentry that's being removed
Summary
| CVE | CVE-2026-98984 |
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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 13:17:20 UTC |
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| Updated | 2026-10-23 13:17:20 UTC |
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| Description | In the Linux kernel, the following vulnerability has been resolved:
dcache: don't put a mountpoint on a dentry that's being removed
rmdir(), unlink() and rename() call dont_mount() on the victim and then
detach_mounts() with the victim's inode locked. do_lock_mount() takes
the inode lock of the mountpoint and checks cant_mount() so a mount
can't show up after detach_mounts().
But attach_recursive_mnt() makes a second mountpoint for the root of the
source mount so that the mounts already located at the destination can
be put on top of it. No inode is locked for that one and d_set_mounted()
only refuses a dentry that is unlinked. Between detach_mounts() and
d_delete() the victim is still hashed:
rmrace: b passed dont_mount() and detach_mounts(), sleeping
T2: move_mount(S, /tmp/plcant/x, BENEATH) = 0 errno 0 ()
T1: rmdir(/tmp/plcant/d/b) = 0 errno 0
109 107 0:61 /d/b//deleted /tmp/plcant/x rw,relatime - tmpfs tmpfs rw
108 109 0:63 / /tmp/plcant/x rw,relatime - tmpfs T rw
A bind mount of the directory that's being removed is moved beneath an
existing mount while the rmdir() is located between the two calls. The
mount ends up on the removed directory and nothing will ever detach it.
Check cant_mount() in d_set_mounted() as well. dont_mount() raises the
flag under d_lock before detach_mounts() runs so either the mountpoint
is set first and detach_mounts() finds the mount or the flag is seen and
the mount is refused. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 1064f874abc0d05eeed8993815f584d847b72486 5e6bfd9f249f2c74bb63c0f06ad959da3bee0971 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1064f874abc0d05eeed8993815f584d847b72486 793cb67b0f52d00c67bd0e76bc57455b5c70ebb8 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1064f874abc0d05eeed8993815f584d847b72486 390ddcea2a8aca411b931a8e2863a80ccca8d2b3 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1064f874abc0d05eeed8993815f584d847b72486 30a1625022411a387cce9239408ece9955bc9c58 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1064f874abc0d05eeed8993815f584d847b72486 75f4197f1e11d2eb75c2d6f916a7d4764db621e5 git |
Not specified |
| CNA |
Linux |
Linux |
affected 5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf git |
Not specified |
| CNA |
Linux |
Linux |
affected 839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7 git |
Not specified |
| CNA |
Linux |
Linux |
affected 808e83e5add13152bd4a88346487de68395c136b git |
Not specified |
| CNA |
Linux |
Linux |
affected 6de9d08a9718ee9c12ba6343c50141c2d633e3dc git |
Not specified |
| CNA |
Linux |
Linux |
affected 4.1.40 4.2 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 4.4.54 4.5 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 4.9.15 4.10 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 4.10.3 4.11 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 4.11 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 4.11 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/75f4197f1e11d2eb75c2d6f916a7d4764db621e5 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/5e6bfd9f249f2c74bb63c0f06ad959da3bee0971 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/390ddcea2a8aca411b931a8e2863a80ccca8d2b3 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/30a1625022411a387cce9239408ece9955bc9c58 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/793cb67b0f52d00c67bd0e76bc57455b5c70ebb8 |
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.