[PATCH] staging: android: ion: Bail out upon SIGKILL when allocating memory.

[Tetsuo Handa]

syzbot found that a thread can stall for minutes inside
ion_system_heap_allocate() after that thread was killed by SIGKILL [1].
Let's check for SIGKILL before doing memory allocation.

[1] https://syzkaller.appspot.com/bug?id=a0e3436829698d5824231251fad9d8e998f94f5e

Signed-off-by: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+8ab2d0f39fb79fe6ca40 at syzkaller.appspotmail.com>
Acked-by: Laura Abbott <labbott at redhat.com>
Acked-by: Sumit Semwal <sumit.semwal at linaro.org>
---
 drivers/staging/android/ion/ion_page_pool.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index fd4995f..f85ec5b1 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -8,11 +8,14 @@
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/swap.h>
+#include <linux/sched/signal.h>
 
 #include "ion.h"
 
 static inline struct page *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
 {
+	if (fatal_signal_pending(current))
+		return NULL;
 	return alloc_pages(pool->gfp_mask, pool->order);
 }
 
-- 
1.8.3.1