From: Mathieu Desnoyers Date: Mon, 2 Jan 2023 15:12:16 +0000 (-0500) Subject: sched/rseq: Fix concurrency ID handling of usermodehelper kthreads X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=bbd0b031509b880b4e9a880bb27ca2a30ad081ab;p=linux.git sched/rseq: Fix concurrency ID handling of usermodehelper kthreads sched_mm_cid_after_execve() does not expect NULL t->mm, but it may happen if a usermodehelper kthread fails when attempting to execute a binary. sched_mm_cid_fork() can be issued from a usermodehelper kthread, which has t->flags PF_KTHREAD set. Fixes: af7f588d8f73 ("sched: Introduce per-memory-map concurrency ID") Reported-by: kernel test robot Reported-by: Borislav Petkov Signed-off-by: Mathieu Desnoyers Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/oe-lkp/202212301353.5c959d72-yujie.liu@intel.com --- diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 048ec2417990a..f99ee69867e3e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -11343,8 +11343,8 @@ void sched_mm_cid_after_execve(struct task_struct *t) struct mm_struct *mm = t->mm; unsigned long flags; - WARN_ON_ONCE((t->flags & PF_KTHREAD) || !t->mm); - + if (!mm) + return; local_irq_save(flags); t->mm_cid = mm_cid_get(mm); t->mm_cid_active = 1; @@ -11354,7 +11354,7 @@ void sched_mm_cid_after_execve(struct task_struct *t) void sched_mm_cid_fork(struct task_struct *t) { - WARN_ON_ONCE((t->flags & PF_KTHREAD) || !t->mm || t->mm_cid != -1); + WARN_ON_ONCE(!t->mm || t->mm_cid != -1); t->mm_cid_active = 1; } #endif