CVE-2026-80671: perf sched: Fix register_pid() overflow, strcpy, and BUG_ON
In the Linux kernel, the following vulnerability has been resolved:
perf sched: Fix registerpid() overflow, strcpy, and BUGON
registerpid() has several issues when processing untrusted perf.data:
1. Integer overflow: (pid + 1) sizeof(struct taskdesc ) can wrap to a small value on 32-bit systems when pid is large (e.g. 0x40000000), causing realloc to return a tiny buffer followed by out-of-bounds writes in the initialization loop.
2. Heap buffer overflow: strcpy(task->comm, comm) copies the untrusted comm string into a fixed 20-byte COMMLEN buffer with no length check.
3. BUGON on allocation failure: perf.data is untrusted input, so allocation failures should be handled gracefully rather than killing the process.
4. Realloc of sched->tasks assigned directly back, leaking the old pointer on failure; nrtasks incremented before the realloc, leaving corrupted state on failure.
Cap pid at PIDMAXLIMIT (4194304, matching the kernel's maximum on 64-bit), replace strcpy with strlcpy, guard against NULL comm, replace BUGON with NULL returns using safe realloc patterns, and add NULL checks in callers that dereference the result.
Affected Software
Event History
Frequently Asked Questions
Who is exposed to this issue?
Systems that use the Linux kernel perf sched tooling to process untrusted perf.data files are exposed. The vulnerable parsing path handles attacker-controlled PID and command-name data from the input file.
What does an attacker need to exploit it?
An attacker needs to provide a crafted perf.data file that is processed by perf sched. A large PID can trigger an allocation-size overflow on 32-bit systems, and an overlong comm string can overflow the fixed-size command-name buffer.
Are 64-bit systems affected by the integer-overflow condition?
The described allocation-size integer overflow is specifically identified for 32-bit systems. The unsafe command-string copy and failure-handling issues arise while processing untrusted perf.data and are not described as limited to 32-bit systems.
What mitigations are available if the fix cannot be applied immediately?
Do not process perf.data files from untrusted sources with perf sched. Restrict use of the tool to trusted capture files until the corrected code is available.