linux-kernel - Re: [PATCH] mm/slub: fix to return errno if kmalloc() fails

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 9 Sep 2022 21:06:11 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     "Vlastimil Babka (SUSE)" <vbabka@...nel.org>
Cc:     Muchun Song <muchun.song@...ux.dev>, Chao Yu <chao@...nel.org>,
        Linux MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, jaegeuk@...nel.org,
        Chao Yu <chao.yu@...o.com>, stable@...nel.org,
        syzbot+81684812ea68216e08c5@...kaller.appspotmail.com,
        David Rientjes <rientjes@...gle.com>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>,
        Christoph Lameter <cl@...ux.com>
Subject: Re: [PATCH] mm/slub: fix to return errno if kmalloc() fails

On Thu, Sep 08, 2022 at 11:25:08PM +0200, Vlastimil Babka (SUSE) wrote:
> > I tend to agree with you. A mount operation shouldn’t panic the
> > kernel.
> 
> Hmm kmalloc(64) shouldn't normally due that due to the the underlying page
> allocation falling into the "too small to fail" category, wonder if
> syzkaller was doing anything special here?

Here's the repro:

https://syzkaller.appspot.com/x/repro.c?x=17cd7fa3080000

you can see it does:

  fd = open("/proc/thread-self/fail-nth", O_RDWR);
  if (fd == -1)
    exit(1);
  char buf[16];
  sprintf(buf, "%d", nth);
  if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))

so this is the kind of stupid nitpicky bug that we shouldn't be
reporting, let alone fixing, IMO.