[PATCH] fix de_thread() vs do_coredump() deadlock

de_thread() sends SIGKILL to all sub-threads and
waits them to die in 'D' state. It is possible that
one of the threads already dequeued coredump signal.
When de_thread() unlocks ->sighand->lock that thread
can enter do_coredump()->coredump_wait() and cause a
deadlock.

Signed-off-by: Oleg Nesterov <[email protected]>

--- 2.6.14-rc4/fs/exec.c~	2005-09-21 21:08:33.000000000 +0400
+++ 2.6.14-rc4/fs/exec.c	2005-10-14 00:19:19.000000000 +0400
@@ -1468,11 +1468,21 @@ int do_coredump(long signr, int exit_cod
 		current->fsuid = 0;	/* Dump root private */
 	}
 	mm->dumpable = 0;
-	init_completion(&mm->core_done);
+
+	retval = -EAGAIN;
 	spin_lock_irq(&current->sighand->siglock);
-	current->signal->flags = SIGNAL_GROUP_EXIT;
-	current->signal->group_exit_code = exit_code;
+	if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {
+		current->signal->flags = SIGNAL_GROUP_EXIT;
+		current->signal->group_exit_code = exit_code;
+		retval = 0;
+	}
 	spin_unlock_irq(&current->sighand->siglock);
+	if (retval) {
+		up_write(&mm->mmap_sem);
+		goto fail;
+	}
+
+	init_completion(&mm->core_done);
 	coredump_wait(mm);
 
 	/*
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

---

• Prev by Date: Re: [PATCH 2/8] Fragmentation Avoidance V17: 002_usemap
• Next by Date: [PATCH] drivers/base - fix sparse warnings
• Previous by thread: [PATCH 1/1] indirect function calls elimination in IO eliminate
• Next by thread: [PATCH] drivers/base - fix sparse warnings
• Index(es):
  • Date
  • Thread

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]