linux-kernel - Re: [PATCH] kexec: Bail out upon SIGKILL when allocating memory.

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Message-ID: <612eebbe-336a-c1d0-904b-5970d3c4dbb0@I-love.SAKURA.ne.jp>
Date:   Mon, 1 Jul 2019 19:52:11 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Eric Biederman <ebiederm@...ssion.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kexec: Bail out upon SIGKILL when allocating memory.

Andrew, can you pick up this patch? We might miss next merge window, for
Eric Biederman seems to be offline for two weeks. 

On 2019/06/14 19:16, Tetsuo Handa wrote:
> 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@...ove.SAKURA.ne.jp>
> Reported-by: syzbot <syzbot+8ab2d0f39fb79fe6ca40@...kaller.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;
>