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md: raid10: Fix null pointer dereference in fix_read_error()

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Such NULL pointer dereference can occur when the driver was fixing the
read errors/bad blocks and the disk was physically removed
causing a system crash. This patch check if the
rcu_dereference() returns valid rdev before accessing it in fix_read_error().

Cc: stable@kernel.org
Signed-off-by: Prasanna S. Panchamukhi <prasanna.panchamukhi@riverbed.com>
Signed-off-by: Rob Becker <rbecker@riverbed.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Prasanna S. Panchamukhi 2010-06-24 13:31:03 +10:00 committed by NeilBrown
parent f3b99be19d
commit 0544a21db0
1 changed files with 6 additions and 6 deletions
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12
drivers/md/raid10.c
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@ -1482,14 +1482,14 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
int sectors = r10_bio->sectors;
mdk_rdev_t*rdev;
int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
int d = r10_bio->devs[r10_bio->read_slot].devnum;
rcu_read_lock();
{
int d = r10_bio->devs[r10_bio->read_slot].devnum;
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev) { /* If rdev is not NULL */
char b[BDEVNAME_SIZE];
int cur_read_error_count = 0;
rdev = rcu_dereference(conf->mirrors[d].rdev);
bdevname(rdev->bdev, b);
if (test_bit(Faulty, &rdev->flags)) {
@ -1530,7 +1530,7 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
rcu_read_lock();
do {
int d = r10_bio->devs[sl].devnum;
d = r10_bio->devs[sl].devnum;
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev &&
test_bit(In_sync, &rdev->flags)) {
@ -1564,7 +1564,7 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
rcu_read_lock();
while (sl != r10_bio->read_slot) {
char b[BDEVNAME_SIZE];
int d;
if (sl==0)
sl = conf->copies;
sl--;
@ -1601,7 +1601,7 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
}
sl = start;
while (sl != r10_bio->read_slot) {
int d;
if (sl==0)
sl = conf->copies;
sl--;