From: Peter Zijlstra <[email protected]> Subject: perf: fix perf bug in fork()
Oleg noticed that a cleanup by Sylvain actually uncovered a bug; by calling perf_event_free_task() when failing sched_fork() we will not yet have done the memset() on ->perf_event_ctxp[] and will therefore try and 'free' the inherited contexts, which are still in use by the parent process. This is bad.. Suggested-by: Oleg Nesterov <[email protected]> Reported-by: Oleg Nesterov <[email protected]> Reported-by: Sylvain 'ythier' Hitier <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- kernel/events/core.c | 4 +++- kernel/fork.c | 5 +++-- 2 files changed, 6 insertions(+), 3 deletions(-) diff -puN kernel/events/core.c~perf-fix-perf-bug-in-fork kernel/events/core.c --- a/kernel/events/core.c~perf-fix-perf-bug-in-fork +++ a/kernel/events/core.c @@ -7948,8 +7948,10 @@ int perf_event_init_task(struct task_str for_each_task_context_nr(ctxn) { ret = perf_event_init_context(child, ctxn); - if (ret) + if (ret) { + perf_event_free_task(child); return ret; + } } return 0; diff -puN kernel/fork.c~perf-fix-perf-bug-in-fork kernel/fork.c --- a/kernel/fork.c~perf-fix-perf-bug-in-fork +++ a/kernel/fork.c @@ -1360,7 +1360,7 @@ static struct task_struct *copy_process( goto bad_fork_cleanup_policy; retval = audit_alloc(p); if (retval) - goto bad_fork_cleanup_policy; + goto bad_fork_cleanup_perf; /* copy all the process information */ shm_init_task(p); retval = copy_semundo(clone_flags, p); @@ -1566,8 +1566,9 @@ bad_fork_cleanup_semundo: exit_sem(p); bad_fork_cleanup_audit: audit_free(p); -bad_fork_cleanup_policy: +bad_fork_cleanup_perf: perf_event_free_task(p); +bad_fork_cleanup_policy: #ifdef CONFIG_NUMA mpol_put(p->mempolicy); bad_fork_cleanup_threadgroup_lock: _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
