Commit 7c3a6aed authored Sep 25, 2019 by Tetsuo Handa Committed by Linus Torvalds Sep 25, 2019

kexec: bail out upon SIGKILL when allocating memory.

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

Link: http://lkml.kernel.org/r/993c9185-d324-2640-d061-bed2dd18b1f7@I-love.SAKURA.ne.jp


Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+8ab2d0f39fb79fe6ca40@syzkaller.appspotmail.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 2a4a4082

kernel/kexec_core.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -300,6 +300,8 @@ 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;

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