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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Eric Biederman <ebiederm@xmission.com>
Cc: syzbot <syzbot+8ab2d0f39fb79fe6ca40@syzkaller.appspotmail.com>,
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: [PATCH] kexec: Bail out upon SIGKILL when allocating memory.
Date: Fri, 14 Jun 2019 19:16:18 +0900
Message-ID: <993c9185-d324-2640-d061-bed2dd18b1f7@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <000000000000c0103a058b2ba0ec@google.com>

syzbot found that a thread can stall for minutes inside kexec_load() after
that thread was killed by SIGKILL [1]. It turned out that the reproducer
was trying to allocate 2408MB of memory using kimage_alloc_page() from
kimage_load_normal_segment(). 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>
Reported-by: syzbot <syzbot+8ab2d0f39fb79fe6ca40@syzkaller.appspotmail.com>
---
 kernel/kexec_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index fd5c95f..2b25d95 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -302,6 +302,8 @@ static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
 {
 	struct page *pages;
 
+	if (fatal_signal_pending(current))
+		return NULL;
 	pages = alloc_pages(gfp_mask & ~__GFP_ZERO, order);
 	if (pages) {
 		unsigned int count, i;
-- 
1.8.3.1


  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-12 20:53 INFO: task syz-executor can't die for more than 143 seconds syzbot
2019-06-13  2:53 ` syzbot
2019-06-14 10:16   ` Tetsuo Handa [this message]
2019-07-01 10:52     ` [PATCH] kexec: Bail out upon SIGKILL when allocating memory Tetsuo Handa
2019-07-24  2:54     ` Eric Biggers
2019-07-24  3:09       ` Tetsuo Handa
2019-06-21  9:58 ` INFO: task syz-executor can't die for more than 143 seconds Tetsuo Handa
2019-07-01 10:55   ` [PATCH] staging: android: ion: Bail out upon SIGKILL when allocating memory Tetsuo Handa
2019-07-01 11:36     ` Laura Abbott
2019-07-01 14:02       ` Sumit Semwal
2019-07-01 21:02         ` Tetsuo Handa
2019-07-01 21:21           ` Laura Abbott

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