proc: protect ptrace_may_access() with exec_update_lock (FD links)

Summary

In the Linux kernel, the following vulnerability has been resolved: proc: protect ptrace_may_access() with exec_update_lock (FD links) proc_pid_get_link() and proc_pid_readlink() currently look up the task from the pid once, then do the ptrace access check on that task, then look up the task from the pid a second time to do the actual access. That's racy in several ways. To fix it, pass the task to the ->proc_get_link() handler, and instead of proc_fd_access_allowed(), introduce a new helper call_proc_get_link() that looks up and locks the task, does the access check, and calls ->proc_get_link().

Timeline

1. Jul 25, 2026, 8:50 AM UTCCVE published
2. Oct 16, 2026, 3:39 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 19, 2026, 8:38 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 778c1144771f0064b6f51bee865cceb0d996f2f9 · fixed in 6253dfee5afba536bb54fc6fe6c091c3758fafe1; From 778c1144771f0064b6f51bee865cceb0d996f2f9 · fixed in 65bf0d2b6e914f1448d6a2fde193dcf60936a651; From 778c1144771f0064b6f51bee865cceb0d996f2f9 · fixed in de497d7aa2fae453a7e7c8f7d3e8682e565e3aaf; From 778c1144771f0064b6f51bee865cceb0d996f2f9 · fixed in 138c692d2b2d63d26f2eb957d0e4fcc5d61f9ff2; From 778c1144771f0064b6f51bee865cceb0d996f2f9 · fixed in 83b17872e3166c295c599279fc9562ac3840c638; From 778c1144771f0064b6f51bee865cceb0d996f2f9 · fixed in 497c6bae5167428596575f20af6613ff5671f383; From 778c1144771f0064b6f51bee865cceb0d996f2f9 · fixed in dfd1894cb64cbd8758b461ed713800fe73db4f82; From 778c1144771f0064b6f51bee865cceb0d996f2f9 · fixed in 6255da28d4bb5349fe18e84cb043ccd394eba75d

• Linux Linux

  2.6.18

• KernelLinux

  From 2.6.18 · fixed in 5.10.261; From 5.11.0 · fixed in 5.15.212; From 5.16.0 · fixed in 6.1.178; From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.4

References 8