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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        syzbot <syzbot+8ab2d0f39fb79fe6ca40@syzkaller.appspotmail.com>,
        Laura Abbott <labbott@redhat.com>,
        Sumit Semwal <sumit.semwal@linaro.org>
Subject: [PATCH 4.19 04/91] staging: android: ion: Bail out upon SIGKILL when allocating memory.
Date:   Wed, 14 Aug 2019 19:00:27 +0200
Message-Id: <20190814165749.236426007@linuxfoundation.org>
In-Reply-To: <20190814165748.991235624@linuxfoundation.org>
References: <20190814165748.991235624@linuxfoundation.org>
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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

commit 8f9e86ee795971eabbf372e6d804d6b8578287a7 upstream.

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@I-love.SAKURA.ne.jp>
Cc: stable <stable@vger.kernel.org>
Reported-by: syzbot <syzbot+8ab2d0f39fb79fe6ca40@syzkaller.appspotmail.com>
Acked-by: Laura Abbott <labbott@redhat.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://lore.kernel.org/r/d088f188-5f32-d8fc-b9a0-0b404f7501cc@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/staging/android/ion/ion_page_pool.c |    3 +++
 1 file changed, 3 insertions(+)

--- 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);
 }