The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 93decc563637c4288380912eac0eb42fb246cc04 Mon Sep 17 00:00:00 2001
From: Kevin Vigor <kvigor@xxxxxxxxx>
Date: Fri, 6 Nov 2020 14:20:34 -0800
Subject: [PATCH] md/raid10: initialize r10_bio->read_slot before use.
In __make_request() a new r10bio is allocated and passed to
raid10_read_request(). The read_slot member of the bio is not
initialized, and the raid10_read_request() uses it to index an
array. This leads to occasional panics.
Fix by initializing the field to invalid value and checking for
valid value in raid10_read_request().
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Kevin Vigor <kvigor@xxxxxxxxx>
Signed-off-by: Song Liu <songliubraving@xxxxxx>
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index b7bca6703df8..3153183b7772 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1127,7 +1127,7 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
struct md_rdev *err_rdev = NULL;
gfp_t gfp = GFP_NOIO;
- if (r10_bio->devs[slot].rdev) {
+ if (slot >= 0 && r10_bio->devs[slot].rdev) {
/*
* This is an error retry, but we cannot
* safely dereference the rdev in the r10_bio,
@@ -1508,6 +1508,7 @@ static void __make_request(struct mddev *mddev, struct bio *bio, int sectors)
r10_bio->mddev = mddev;
r10_bio->sector = bio->bi_iter.bi_sector;
r10_bio->state = 0;
+ r10_bio->read_slot = -1;
memset(r10_bio->devs, 0, sizeof(r10_bio->devs[0]) * conf->geo.raid_disks);
if (bio_data_dir(bio) == READ)
