ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock
In the Linux kernel, the following vulnerability has been resolved: ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock list_for_each_entry() iterates ci->i_cap_flush_list but drops i_ceph_lock to send cap messages. During the unlock window, handle_cap_flush_ack() can acquire i_ceph_lock, detach cf entries with tid <= flush_tid from the list, release i_ceph_lock, and free them via ceph_free_cap_flush() outside any lock. When the original thread reacquires i_ceph_lock and the for-loop macro advances via cf = list_next_entry(cf, i_list), it dereferences cf->i_list.next on freed memory. The race timeline: __kick_flushing_caps() handle_cap_flush_ack() ----------------------- ----------------------- holds i_ceph_lock <--- iterates to cf (tid=10) prepares FLUSH message drops i_ceph_lock <--- __send_cap() ── FLUSH(tid=10) MDS sends FLUSH_ACK(tid=10) ---> acquires i_ceph_lock cf->tid(10) <= flush_tid(10), detaches cf from i_cap_flush_list drops i_ceph_lock ceph_free_cap_flush(cf) <- frees it! acquires i_ceph_lock <--- for-loop advances: cf = list_next_entry(cf, i_list) -- UAF on freed cf->i_list.next The cf was just sent by __kick_flushing_caps itself via __send_cap(). The MDS may respond with FLUSH_ACK quickly enough that handle_cap_flush_ack() frees cf before __kick_flushing_caps can finish the iteration. Fix by converting to a manual while loop: save the next pointer under i_ceph_lock before dropping it, then use the saved pointer after reacquiring, so the pote
CVE-2026-89655
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-89655
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "e4500b5e35c213e0f97be7cb69328c0877203a79",
"lessThan": "091137821e1fc88f37e15201abf055c9494ddc61",
"versionType": "git"
},
{
"status": "affected",
"version": "e4500b5e35c213e0f97be7cb69328c0877203a79",
"lessThan": "01542430081014d80fc9e70e92d6647432ddb7fc",
"versionType": "git"
},
{
"status": "affected",
"version": "e4500b5e35c213e0f97be7cb69328c0877203a79",
"lessThan": "23eb34a53a53cb1a6dab1eeee830633207ac158d",
"versionType": "git"
},
{
"status": "affected",
"version": "e4500b5e35c213e0f97be7cb69328c0877203a79",
"lessThan": "19f16f04c2b014a7dd214dc1e42557d8530b16f3",
"versionType": "git"
},
{
"status": "affected",
"version": "e4500b5e35c213e0f97be7cb69328c0877203a79",
"lessThan": "2701431aa3cc8b23efe6890182e7b04f5e76fab5",
"versionType": "git"
},
{
"status": "affected",
"version": "e4500b5e35c213e0f97be7cb69328c0877203a79",
"lessThan": "fe46746087b5b9c5bb2d022df6c7819218494ced",
"versionType": "git"
},
{
"status": "affected",
"version": "e4500b5e35c213e0f97be7cb69328c0877203a79",
"lessThan": "2dba24dcd5050be4b7b119e6f0b01f62203b5d26",
"versionType": "git"
},
{
"status": "affected",
"version": "e4500b5e35c213e0f97be7cb69328c0877203a79",
"lessThan": "7af4c4f01305b0935adf6d4301b1ec407025485d",
"versionType": "git"
}
],
"programFiles": [
"fs/ceph/caps.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.8"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.8",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/ceph/caps.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89655
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #35148 · Revision 1
- Added to Heist Feed
- Publisher date