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 D5D022E337A; Tue, 8 Jul 2025 16:43:15 +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=1751992995; cv=none; b=nmmD4uUNal+eLvElXQTVHgEchxo4zm8933YisBAVzCfj1f2GFIqEBihsN2s+wThVMQ2jRTiJvnzMrfcM1oQZB/wSfWGeZzn8ulmu2iTBAiIvl2k1q3dZjM2wq/n2cdfd09MSHHbryeTTFslpD/k2z+c9aj4BHD4kYnsJdRBSnYQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751992995; c=relaxed/simple; bh=IKNCQMFSy/+vys7ZqtIGDE3JNL+s+xsJEgG5sYesM10=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Arp1QWDItpYwicJU1NmhK+GbNPQVKkk3SPQjBQHff47f+OX4ZZGRpdZCjJ2XrZKQ5ztQcsUmAxSrEFtYRhK7GRtcvzjw+cwka7/rBpVRo/ltfCe4WH0XtY6koOZWyWf0FC9jiBsL8LKebOE6xM+skuPVpHJUn6bx0KXN6+Fn57k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dzCuC2vO; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="dzCuC2vO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A6B6C4CEED; Tue, 8 Jul 2025 16:43:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1751992995; bh=IKNCQMFSy/+vys7ZqtIGDE3JNL+s+xsJEgG5sYesM10=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dzCuC2vOBJ0SX97PGF1NPdpG9dZ1tZe3k/h7K/Gfb3GaIE6lxPH+LM7cs6hGXtST8 UktnieAfef+8M/0L8WWsewcDYwuiPGkUjEtfD2GTBNFeND59PidiUhtQURPdg+umSb qQtO0mN3+4gcsT4K04F6ZjtikzJ81x69g71cBD0A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+25b83a6f2c702075fcbc@syzkaller.appspotmail.com, David Howells , Paulo Alcantara , netfs@lists.linux.dev, linux-fsdevel@vger.kernel.org, Christian Brauner , Sasha Levin Subject: [PATCH 6.12 151/232] netfs: Fix oops in write-retry from mis-resetting the subreq iterator Date: Tue, 8 Jul 2025 18:22:27 +0200 Message-ID: <20250708162245.390650881@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250708162241.426806072@linuxfoundation.org> References: <20250708162241.426806072@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Howells [ Upstream commit 4481f7f2b3df123ec77e828c849138f75cff2bf2 ] Fix the resetting of the subrequest iterator in netfs_retry_write_stream() to use the iterator-reset function as the iterator may have been shortened by a previous retry. In such a case, the amount of data to be written by the subrequest is not "subreq->len" but "subreq->len - subreq->transferred". Without this, KASAN may see an error in iov_iter_revert(): BUG: KASAN: slab-out-of-bounds in iov_iter_revert lib/iov_iter.c:633 [inline] BUG: KASAN: slab-out-of-bounds in iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611 Read of size 4 at addr ffff88802912a0b8 by task kworker/u32:7/1147 CPU: 1 UID: 0 PID: 1147 Comm: kworker/u32:7 Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: events_unbound netfs_write_collection_worker Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 iov_iter_revert lib/iov_iter.c:633 [inline] iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611 netfs_retry_write_stream fs/netfs/write_retry.c:44 [inline] netfs_retry_writes+0x166d/0x1a50 fs/netfs/write_retry.c:231 netfs_collect_write_results fs/netfs/write_collect.c:352 [inline] netfs_write_collection_worker+0x23fd/0x3830 fs/netfs/write_collect.c:374 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Fixes: cd0277ed0c18 ("netfs: Use new folio_queue data type and iterator instead of xarray iter") Reported-by: syzbot+25b83a6f2c702075fcbc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=25b83a6f2c702075fcbc Signed-off-by: David Howells Link: https://lore.kernel.org/20250519090707.2848510-2-dhowells@redhat.com Tested-by: syzbot+25b83a6f2c702075fcbc@syzkaller.appspotmail.com cc: Paulo Alcantara cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/netfs/write_collect.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c index 412d4da742270..7cb21da40a0a4 100644 --- a/fs/netfs/write_collect.c +++ b/fs/netfs/write_collect.c @@ -176,9 +176,10 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq, if (test_bit(NETFS_SREQ_FAILED, &subreq->flags)) break; if (__test_and_clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) { - struct iov_iter source = subreq->io_iter; + struct iov_iter source; - iov_iter_revert(&source, subreq->len - source.count); + netfs_reset_iter(subreq); + source = subreq->io_iter; __set_bit(NETFS_SREQ_RETRYING, &subreq->flags); netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit); netfs_reissue_write(stream, subreq, &source); -- 2.39.5