[PATCH 3.11 076/137] coredump: fix the setting of PF_DUMPCORE

[Luis Henriques]

3.11.10.15 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Silesh C V <svellattu at mvista.com>

commit aed8adb7688d5744cb484226820163af31d2499a upstream.

Commit 079148b919d0 ("coredump: factor out the setting of PF_DUMPCORE")
cleaned up the setting of PF_DUMPCORE by removing it from all the
linux_binfmt->core_dump() and moving it to zap_threads().But this ended
up clearing all the previously set flags.  This causes issues during
core generation when tsk->flags is checked again (eg.  for PF_USED_MATH
to dump floating point registers).  Fix this.

Signed-off-by: Silesh C V <svellattu at mvista.com>
Acked-by: Oleg Nesterov <oleg at redhat.com>
Cc: Mandeep Singh Baines <msb at chromium.org>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/coredump.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/coredump.c b/fs/coredump.c
index 729a2ededcb9..b2fa3937a7eb 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -302,7 +302,7 @@ static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
 	if (unlikely(nr < 0))
 		return nr;
 
-	tsk->flags = PF_DUMPCORE;
+	tsk->flags |= PF_DUMPCORE;
 	if (atomic_read(&mm->mm_users) == nr + 1)
 		goto done;
 	/*
-- 
1.9.1