reboot: fix cad_pid use-after-free race
In the Linux kernel, the following vulnerability has been resolved: reboot: fix cad_pid use-after-free race cad_pid is a single kernel-wide struct pid pointer. proc_do_cad_pid() reads it and passes it to pid_vnr() without protecting the lifetime of the referenced struct pid. A concurrent writer can replace cad_pid and drop the final reference to the old struct pid after the reader has loaded the pointer but before pid_vnr() has finished dereferencing it, causing a use-after-free. kill_cad_pid() has the same lifetime race when it passes cad_pid to kill_pid(). At the time this issue was reported, an unprivileged user could reach the sysctl through user and PID namespaces because cad_pid was registered in pid_table[]. Moving cad_pid back to the global reboot sysctl table corrected that namespace and permission mismatch, but did not fix the underlying lifetime race. Fix this by treating cad_pid as an RCU-protected pointer at both read sites and by waiting for a grace period before dropping the old reference on the write side. call_rcu(&old_pid->rcu, ...) cannot be used here because free_pid() also queues pid->rcu; queueing the same rcu_head twice can corrupt the RCU callback list. Original KASAN crash stack: kernel/pid.c:545 pid_nr_ns() # reads freed pid->level kernel/pid.c:556 pid_vnr() # calls pid_nr_ns() kernel/pid.c:775 proc_do_cad_pid() # calls pid_vnr(cad_pid)
CVE-2026-97938
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-2026-97938
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": "9ec52099e4b8678a60e9f93e41ad87885d64f3e6",
"lessThan": "0c1a966bc047af2801a70b8eb13f9df5d7ab925f",
"versionType": "git"
},
{
"status": "affected",
"version": "9ec52099e4b8678a60e9f93e41ad87885d64f3e6",
"lessThan": "ae3e53fe3c1241855e3a88f74877738349948c78",
"versionType": "git"
},
{
"status": "affected",
"version": "9ec52099e4b8678a60e9f93e41ad87885d64f3e6",
"lessThan": "ad72e2566643fff7f01666d845fb026898155e1f",
"versionType": "git"
},
{
"status": "affected",
"version": "9ec52099e4b8678a60e9f93e41ad87885d64f3e6",
"lessThan": "9a17b0e053197a6a42cdc75e75a35b17aa662088",
"versionType": "git"
},
{
"status": "affected",
"version": "9ec52099e4b8678a60e9f93e41ad87885d64f3e6",
"lessThan": "5a88f78df753993469dab4d1831f8fb4256a9468",
"versionType": "git"
}
],
"programFiles": [
"include/linux/sched.h",
"include/linux/sched/signal.h",
"init/main.c",
"kernel/reboot.c",
"kernel/signal.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.19"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.19",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.112",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.53",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.7",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"include/linux/sched.h",
"include/linux/sched/signal.h",
"init/main.c",
"kernel/reboot.c",
"kernel/signal.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-97938
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #48811 · Revision 1
- Added to Heist Feed
- Publisher date