From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Eric Biggers <ebiggers@kernel.org>
Cc: linux-security-module@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: Reminder: 2 open syzbot bugs in "security/tomoyo" subsystem
Date: Wed, 24 Jul 2019 13:54:40 +0900 [thread overview]
Message-ID: <737a46de-cfb0-6220-c796-563ffd3ff325@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20190724043450.GZ643@sol.localdomain>
On 2019/07/24 13:34, Eric Biggers wrote:
> On Wed, Jul 24, 2019 at 12:18:47PM +0900, Tetsuo Handa wrote:
>>> --------------------------------------------------------------------------------
>>> Title: KASAN: invalid-free in tomoyo_realpath_from_path
>>> Last occurred: 57 days ago
>>> Reported: 56 days ago
>>> Branches: net-next
>>> Dashboard link: https://syzkaller.appspot.com/bug?id=e9e5a1d41c3fb5d0f79aeea0e4cd535f160a6702
>>> Original thread: https://lkml.kernel.org/lkml/000000000000785e9d0589ec359a@google.com/T/#u
>>
>> This cannot be a TOMOYO's bug. We are waiting for a reproducer but
>> no crash occurred since then. Maybe it is time to close as invalid.
>
> Maybe. Did you check for stack buffer overflows in the functions that
> tomoyo_realpath_from_path() calls? Perhaps something is corrupting the 'buf'
> variable in the parent's stack frame.
>
What do you mean? If this crash were a stack buffer overflow, this crash
should have already occurred again.
Since the "buf" variable is a local variable, it cannot be shared between
two threads. Since "buf" is assigned as
buf = kmalloc(buf_len, GFP_NOFS);
and nobody else is reassigning "buf",
kfree(buf);
can't become an invalid free.
next prev parent reply other threads:[~2019-07-24 4:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-24 2:42 Reminder: 2 open syzbot bugs in "security/tomoyo" subsystem Eric Biggers
2019-07-24 3:18 ` Tetsuo Handa
2019-07-24 4:34 ` Eric Biggers
2019-07-24 4:54 ` Tetsuo Handa [this message]
2019-07-24 5:00 ` Eric Biggers
-- strict thread matches above, loose matches on Subject: below --
2019-07-02 5:14 Eric Biggers
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