From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8986CF9C0; Sat, 5 Jul 2025 02:18:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751681880; cv=none; b=pGCBkEQkPZo3t4m2+obhLSMqRhnRzAqSMfmfW9mcnOXGYtfhAGmCbKQPKkIZFNlaCTTTFYQuzi8hS+HCznY1HEBFlP9nis8uj2BAu9kLr8E+6Xq8cBd7CgfqoBE0MOfbiAfSctHma5FK9P51R5mWZlhwve1OQZFw2P/VqgY3/PU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751681880; c=relaxed/simple; bh=KLjzJvmcBlWpVpZts+62XfmqQ3g7Cx0jAYoobQykBWQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ErI0svsGcqFFpsVV0l9IeJsJqVdGqlAThJiP6lB5UYIA9H3+yJ9dIGFy4OLxfV29HUghmYceA0dc73uUTzdrCcUrFSfDeH3AJyexMEoLmS/BpKEjVyH9BR1LfdR9FLSqoZde4LK6RP9eYnMGEQltPf96Ibw3T2hMEUqYMLgb900= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VzETWLqj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VzETWLqj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9EE1C4CEE3; Sat, 5 Jul 2025 02:17:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751681880; bh=KLjzJvmcBlWpVpZts+62XfmqQ3g7Cx0jAYoobQykBWQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VzETWLqjWZcKNCgqZ4QwJI8Y8jNIC8TpkG3aA0Dg9PMGymVZ3TZnIcm0Wb1SiOzGZ XllzMlAJkoQyvhtxNX2hwbZDUdKb12OcouivgEEr0Y+85oG6KvFProfFCPK1XZKDfR nu2Mf9pT59RBIU6DXd3RJIyrTJEH8Jhs/np6BWGWFQcKfgWIh6iChcJePC4Wp3UTHz /xjVhl3DvZBC8xPtPAn5D1S1xRJPOWy6yYYLbEkfi763bDdlInLn8f7ZoOjGNJses3 913qVza8FoCm6n5nAf5Q4lLDFRfqIZ2dsqzkxhwh5Vn0VjIYbrFo0RBFKtQOD36RP4 l/HXzUENQ9z3A== Date: Fri, 4 Jul 2025 19:17:58 -0700 From: Luis Chamberlain To: syzbot Cc: axboe@kernel.dk, brauner@kernel.org, hare@suse.de, hirofumi@mail.parknet.co.jp, linkinjeon@kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, sj1557.seo@samsung.com, syzkaller-bugs@googlegroups.com, willy@infradead.org, p.raghav@samsung.com Subject: Re: [syzbot] [exfat?] kernel BUG in folio_set_bh Message-ID: References: <6865e87a.a70a0220.2b31f5.000a.GAE@google.com> <68663a26.a70a0220.5d25f.0856.GAE@google.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <68663a26.a70a0220.5d25f.0856.GAE@google.com> On Thu, Jul 03, 2025 at 01:07:02AM -0700, syzbot wrote: > syzbot has bisected this issue to: > > commit 47dd67532303803a87f43195e088b3b4bcf0454d > Author: Luis Chamberlain > Date: Fri Feb 21 22:38:22 2025 +0000 > > block/bdev: lift block size restrictions to 64k > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15ec33d4580000 > start commit: 50c8770a42fa Add linux-next specific files for 20250702 > git tree: linux-next > final oops: https://syzkaller.appspot.com/x/report.txt?x=17ec33d4580000 > console output: https://syzkaller.appspot.com/x/log.txt?x=13ec33d4580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d831c9dfe03f77ec > dashboard link: https://syzkaller.appspot.com/bug?extid=f4f84b57a01d6b8364ad > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15c93770580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1001aebc580000 > > Reported-by: syzbot+f4f84b57a01d6b8364ad@syzkaller.appspotmail.com > Fixes: 47dd67532303 ("block/bdev: lift block size restrictions to 64k") > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection Odd, I can't see where the null pointer comes from. bdev_getblk() --> __getblk_slow() properly returns NULL and doesn't use the data. But neither does fat_fill_super() on failure. My only suspicion was on fat_msg() but that sb usage seems fine and the goto out_fail seems fine as iput() also doesn't process null inodes and unload_nls() is fine. The return value is also set to -EIO correctly so we don't return NULL actually. I jus tdon't see anything odd on _fat_msg() either. Hrm.. Luis