From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, NeilBrown , Yufen Yu , Shaohua Li , Sasha Levin Subject: [PATCH 4.9 120/329] md raid10: fix NULL deference in handle_write_completed() Date: Mon, 28 May 2018 12:00:49 +0200 Message-Id: <20180528100252.691476190@linuxfoundation.org> In-Reply-To: <20180528100241.796630982@linuxfoundation.org> References: <20180528100241.796630982@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yufen Yu [ Upstream commit 01a69cab01c184d3786af09e9339311123d63d22 ] In the case of 'recover', an r10bio with R10BIO_WriteError & R10BIO_IsRecover will be progressed by handle_write_completed(). This function traverses all r10bio->devs[copies]. If devs[m].repl_bio != NULL, it thinks conf->mirrors[dev].replacement is also not NULL. However, this is not always true. When there is an rdev of raid10 has replacement, then each r10bio ->devs[m].repl_bio != NULL in conf->r10buf_pool. However, in 'recover', even if corresponded replacement is NULL, it doesn't clear r10bio ->devs[m].repl_bio, resulting in replacement NULL deference. This bug was introduced when replacement support for raid10 was added in Linux 3.3. As NeilBrown suggested: Elsewhere the determination of "is this device part of the resync/recovery" is made by resting bio->bi_end_io. If this is end_sync_write, then we tried to write here. If it is NULL, then we didn't try to write. Fixes: 9ad1aefc8ae8 ("md/raid10: Handle replacement devices during resync.") Cc: stable (V3.3+) Suggested-by: NeilBrown Signed-off-by: Yufen Yu Signed-off-by: Shaohua Li Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/md/raid10.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -2636,7 +2636,8 @@ static void handle_write_completed(struc for (m = 0; m < conf->copies; m++) { int dev = r10_bio->devs[m].devnum; rdev = conf->mirrors[dev].rdev; - if (r10_bio->devs[m].bio == NULL) + if (r10_bio->devs[m].bio == NULL || + r10_bio->devs[m].bio->bi_end_io == NULL) continue; if (!r10_bio->devs[m].bio->bi_error) { rdev_clear_badblocks( @@ -2651,7 +2652,8 @@ static void handle_write_completed(struc md_error(conf->mddev, rdev); } rdev = conf->mirrors[dev].replacement; - if (r10_bio->devs[m].repl_bio == NULL) + if (r10_bio->devs[m].repl_bio == NULL || + r10_bio->devs[m].repl_bio->bi_end_io == NULL) continue; if (!r10_bio->devs[m].repl_bio->bi_error) {