Commit f8bd4798 authored Nov 06, 2020 by Kevin Vigor Committed by Greg Kroah-Hartman Jan 06, 2021

md/raid10: initialize r10_bio->read_slot before use.



commit 93decc563637c4288380912eac0eb42fb246cc04 upstream.

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@vger.kernel.org
Signed-off-by: Kevin Vigor <kvigor@gmail.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 3207316b

drivers/md/raid10.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1138,7 +1138,7 @@ 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,
		@@ -1547,6 +1547,7 @@ 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->copies);

		if (bio_data_dir(bio) == READ)