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.
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.
Metrics
Affected Vendors & Products
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Fixes
Solution
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Workaround
No workaround given by the vendor.
References
History
Fri, 23 Oct 2026 17:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-617 |
Fri, 23 Oct 2026 12:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | dcache: don't put a mountpoint on a dentry that's being removed | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-10-23T12:20:02.285Z
Reserved: 2026-09-25T10:25:14.384Z
Link: CVE-2026-98984
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-10-23T13:17:20.287
Modified: 2026-10-23T13:17:20.287
Link: CVE-2026-98984
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-10-23T17:00:15Z
Weaknesses