Linux vulnerability

What happened

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().

Affected versions

Linux: 778c1144771f0064b6f51bee865cceb0d996f2f9 through before 6253dfee5afba536bb54fc6fe6c091c3758fafe1 (git); 778c1144771f0064b6f51bee865cceb0d996f2f9 through before 65bf0d2b6e914f1448d6a2fde193dcf60936a651 (git); 778c1144771f0064b6f51bee865cceb0d996f2f9 through before de497d7aa2fae453a7e7c8f7d3e8682e565e3aaf (git); 778c1144771f0064b6f51bee865cceb0d996f2f9 through before 138c692d2b2d63d26f2eb957d0e4fcc5d61f9ff2 (git); 778c1144771f0064b6f51bee865cceb0d996f2f9 through before 83b17872e3166c295c599279fc9562ac3840c638 (git); 778c1144771f0064b6f51bee865cceb0d996f2f9 through before 497c6bae5167428596575f20af6613ff5671f383 (git); 778c1144771f0064b6f51bee865cceb0d996f2f9 through before dfd1894cb64cbd8758b461ed713800fe73db4f82 (git); 778c1144771f0064b6f51bee865cceb0d996f2f9 through before 6255da28d4bb5349fe18e84cb043ccd394eba75d (git); 2.6.18; V3.1.6 through before * (custom) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.