From: Kyle Zeng <kylebot@openai.com> mainline inclusion from mainline-v7.2 commit fa091f46c3833fb22384f10eade2b4e1e1d0b278 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18336 CVE: CVE-2026-74753 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... ---------------------------------------------------------------------- perf_event_remove_on_exec() sets remove-on-exec events to the EXIT state and detaches their group relationships. The event's file descriptor can remain open, however, and perf_event_open() currently accepts that event as a group leader because its early validation rejects only REVOKED and DEAD events. A new sibling can consequently be linked to the detached leader. When the leader is closed, perf_group_detach() observes that its PERF_ATTACH_GROUP bit is already clear and skips the new sibling. The sibling then retains a group_leader pointer to the freed event. Reject group leaders in the EXIT state. Perform the check while holding the shared context mutex so that an exec in the target task cannot detach the leader between validation and group attachment. [peterz: make the earlier test fully consistent] Fixes: 037a3c43edfb ("perf/core: Detach event groups during remove_on_exec") Assisted-by: Codex:gpt-5.6-sol Signed-off-by: Kyle Zeng <kylebot@openai.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260806205655.75722-1-kylebot@openai.com Conflicts: kernel/events/core.c [Upstream fa091f46c3833 ("perf: Reject exited events as group leaders") rejects EXIT-state group leaders in two spots: the early fd validation and a recheck under ctx::mutex. The downstream baseline predates the fd_file()/PERF_EVENT_STATE_REVOKED refactor present in the upstream base: there is no fd_file() helper and no REVOKED event-state in the downstream enum (only PERF_EVENT_STATE_EXIT). Keep the downstream perf_fget_light()/group.file->private_data accessor instead of the absent fd_file(group), and add the EXIT-state rejection with -ENODEV/goto err_fd right after retrieving the leader. This achieves the same early-validation safety as the upstream change. The second hunk (recheck under ctx::mutex with goto err_locked) applies verbatim.] Signed-off-by: Luo Gengkun <luogengkun2@huawei.com> --- kernel/events/core.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 6916dc78b0e7..a388eb764659 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -12678,6 +12678,10 @@ SYSCALL_DEFINE5(perf_event_open, if (err) goto err_fd; group_leader = group.file->private_data; + if (group_leader->state <= PERF_EVENT_STATE_EXIT) { + err = -ENODEV; + goto err_group_fd; + } if (flags & PERF_FLAG_FD_OUTPUT) output_event = group_leader; if (flags & PERF_FLAG_FD_NO_GROUP) @@ -12805,6 +12809,12 @@ SYSCALL_DEFINE5(perf_event_open, if (group_leader->ctx != ctx) goto err_locked; + /* Recheck under ctx::mutex to serialize against remove-on-exec. */ + if (group_leader->state <= PERF_EVENT_STATE_EXIT) { + err = -ENODEV; + goto err_locked; + } + /* * Only a group leader can be exclusive or pinned */ -- 2.34.1