From: David Howells <dhowells@redhat.com>
To: Sven Schnelle <svens@linux.ibm.com>
Cc: dhowells@redhat.com,
syzbot <syzbot+9b82859567f2e50c123e@syzkaller.appspotmail.com>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, syzkaller-bugs@googlegroups.com,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
linux-crypto@vger.kernel.org
Subject: Re: [syzbot] [mm?] WARNING in try_grab_page
Date: Tue, 25 Jul 2023 10:28:31 +0100 [thread overview]
Message-ID: <35256.1690277311@warthog.procyon.org.uk> (raw)
In-Reply-To: <yt9d8rb44cbe.fsf@linux.ibm.com>
Sven Schnelle <svens@linux.ibm.com> wrote:
>
> I looked into this issue. What syzkaller is doing is opening an AF_ALG
> socket, and sending a large message which will eventually end in -EFAULT.
> Looking at the code in crypto/algif_hash.c i see that hash_sendmsg is
> calling extract_iter_to_sg() -> extract_user_to_sg(). In the -EFAULT
> case, this function is calling put_page(), which looks like a leftover
> from the old pinning interface. I think this should be a
> unpin_user_page() call now.
>
> However, hash_sendmsg() also unpins via af_alg_free_sg() in the error
> path. From an API perspective, i would prefer if extract_user_to_sg()
> does the unpinning on error. Any thoughts?
Good catch, thanks. I'll whip up a patch or two for it.
David
next prev parent reply other threads:[~2023-07-25 9:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-03 16:34 syzbot
2023-07-25 8:36 ` Sven Schnelle
2023-07-25 9:28 ` David Howells [this message]
2023-07-26 8:25 ` David Howells
2023-09-05 17:36 ` syzbot
[not found] <125377.1690360290@warthog.procyon.org.uk>
2023-07-26 8:31 ` syzbot
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