reboot: fix cad_pid use-after-free race
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.6.160, 6.12.112, 6.18.53, 7.2.7
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
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)
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 · fixed in 0c1a966bc047af2801a70b8eb13f9df5d7ab925f; From 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 · fixed in ae3e53fe3c1241855e3a88f74877738349948c78; From 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 · fixed in ad72e2566643fff7f01666d845fb026898155e1f; From 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 · fixed in 9a17b0e053197a6a42cdc75e75a35b17aa662088; From 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 · fixed in 5a88f78df753993469dab4d1831f8fb4256a9468
- Linux Linux
2.6.19
- KernelLinux
From 2.6.19 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.112; From 6.13.0 · fixed in 6.18.53; From 6.19.0 · fixed in 7.2.7