From: Andrew Morton <akpm@linux-foundation.org>
To: Wang Cheng <wanngchenng@gmail.com>
Cc: linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
syzbot+ad1b8c404f0959c4bfcc@syzkaller.appspotmail.com
Subject: Re: [PATCH] mm/mempolicy: fix uninit-value in mpol_rebind_policy()
Date: Tue, 17 May 2022 17:08:17 -0700 [thread overview]
Message-ID: <20220517170817.94ca21558bbe035ae06bf6fa@linux-foundation.org> (raw)
In-Reply-To: <20220516094726.b5rrsjg7rvei2od5@ppc.localdomain>
On Mon, 16 May 2022 17:47:26 +0800 Wang Cheng <wanngchenng@gmail.com> wrote:
>
> ...
>
> This patch seems to fix below bug too.
> KMSAN: uninit-value in mpol_rebind_mm (2)
> https://syzkaller.appspot.com/bug?id=f2fecd0d7013f54ec4162f60743a2b28df40926b
>
> The uninit-value is pol->w.cpuset_mems_allowed in mpol_rebind_policy().
> When syzkaller reproducer runs to the beginning of mpol_new(),
>
> mpol_new() mm/mempolicy.c
> do_mbind() mm/mempolicy.c
> kernel_mbind() mm/mempolicy.c
>
> `mode` is 1(MPOL_PREFERRED), nodes_empty(*nodes) is `true` and `flags`
> is 0. Then
>
> mode = MPOL_LOCAL;
> ...
> policy->mode = mode;
> policy->flags = flags;
>
> will be executed. So in mpol_set_nodemask(),
>
> mpol_set_nodemask() mm/mempolicy.c
> do_mbind()
> kernel_mbind()
>
> pol->mode is 4(MPOL_LOCAL), that `nodemask` in `pol` is not initialized,
> which will be accessed in mpol_rebind_policy().
Thanks, I added the above to the changelog and I plan to import the
result into mm-stable later this week.
> IIUC, "#syz fix: mm/mempolicy: fix uninit-value in mpol_rebind_policy()"
> could be sent to syzbot+ad1b8c404f0959c4bfcc@syzkaller.appspotmail.com
> to attach the fixing commit to the bug. WDYT?
Could be. The "syz fix" isn't a thing I've paid much attention to.
I'll start doing so ;)
next prev parent reply other threads:[~2022-05-18 0:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-12 12:34 [PATCH] mm/mempolicy: fix uninit-value in mpol_rebind_policy() Wang Cheng
2022-05-16 9:47 ` Wang Cheng
2022-05-18 0:08 ` Andrew Morton [this message]
2022-05-18 8:52 ` Dmitry Vyukov
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