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

commit 93decc5636 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>
5.4-rM2-2.2.x-imx-squashed
Kevin Vigor 2020-11-06 14:20:34 -08:00 committed by Greg Kroah-Hartman
parent c71c512f4a
commit d3076d054f
1 changed files with 2 additions and 1 deletions
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3
drivers/md/raid10.c
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@ -1145,7 +1145,7 @@ 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,
@ -1510,6 +1510,7 @@ 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)