From 01a69cab01c184d3786af09e9339311123d63d22 Mon Sep 17 00:00:00 2001 From: Yufen Yu Date: Tue, 6 Feb 2018 17:39:15 +0800 Subject: [PATCH] md raid10: fix NULL deference in handle_write_completed() 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 --- drivers/md/raid10.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 8d7ddc947d9d..9e9441fde8b3 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -2655,7 +2655,8 @@ static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio) 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_status) { rdev_clear_badblocks( @@ -2670,7 +2671,8 @@ static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio) 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_status) {