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 737171ADC97; Tue, 17 Jun 2025 16:41:53 +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=1750178513; cv=none; b=s+XLA4nXev+a2MzfjFFPSwZWYfWEKk5DMXjpliZBSAqLxKGV8AIzHX5GOsOUaJ+vFZ4Bap7tX6aE/6U9CBysTg4ha+MCXKGi4I8uXtB6z3wuuwvD4SAN+5H37oumuoFllJqi1i25RinqMmJiIBoBKT5NAblZDHmCX5PsGQi2O2Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750178513; c=relaxed/simple; bh=abDzn3/HuW9FrQlHz+9AyJ3SUWrN2ItQN3YuRAJJunI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ni30HnxxCU6mscxj/pkaGSaTyUKa2hcNEDKj2E7+uWcxTmsosKU8rcHZMQLmq3yPRBXLBAWKHVveIZGyFskG4pyejtiYcn2sYvMLNn0tX7/5IPOPBOF4WHhSW2fFoTFNDdZePaZ2RK2fvxBIqf3MyHSkO38WYo9whh+vjbGqJgk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=kzLVlFE+; 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="kzLVlFE+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6427C4CEE3; Tue, 17 Jun 2025 16:41:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1750178513; bh=abDzn3/HuW9FrQlHz+9AyJ3SUWrN2ItQN3YuRAJJunI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kzLVlFE+goJp6k6TODFuAuRDbdR0A/yjmr5jpb0TTm05DykqnRDAEOQTBUHc3PJb+ 59ytng4Y76t4W1pEJUTRqA2VNnNeTuKz1O0kQ3Fj3douica7mVPI+6ETnlIG0IOIlH 16bjuoH4Q621orYX6+J3ajfKCEvAP8bEsVE1JQuI= 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 6.15 453/780] netfs: Fix oops in write-retry from mis-resetting the subreq iterator Date: Tue, 17 Jun 2025 17:22:41 +0200 Message-ID: <20250617152509.915938838@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250617152451.485330293@linuxfoundation.org> References: <20250617152451.485330293@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 6.15-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_retry.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/netfs/write_retry.c b/fs/netfs/write_retry.c index 545d33079a77d..9b1ca8b0f4dd6 100644 --- a/fs/netfs/write_retry.c +++ b/fs/netfs/write_retry.c @@ -39,9 +39,10 @@ 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; netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit); netfs_reissue_write(stream, subreq, &source); } -- 2.39.5