[PATCH 10/29] drivers, md: convert stripe_head.count from atomic_t to refcount_t

From: Elena Reshetova
Date: Mon Mar 06 2017 - 09:26:21 EST

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@xxxxxxxxx>
Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
---
drivers/md/raid5-cache.c | 8 +++---
drivers/md/raid5.c | 66 ++++++++++++++++++++++++------------------------
drivers/md/raid5.h | 3 ++-
3 files changed, 39 insertions(+), 38 deletions(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 3f307be..6c05e12 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -979,7 +979,7 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
* don't delay.
*/
clear_bit(STRIPE_DELAYED, &sh->state);
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);

mutex_lock(&log->io_mutex);
/* meta + data */
@@ -1321,7 +1321,7 @@ static void r5c_flush_stripe(struct r5conf *conf, struct stripe_head *sh)
assert_spin_locked(&conf->device_lock);

list_del_init(&sh->lru);
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);

set_bit(STRIPE_HANDLE, &sh->state);
atomic_inc(&conf->active_stripes);
@@ -1424,7 +1424,7 @@ static void r5c_do_reclaim(struct r5conf *conf)
*/
if (!list_empty(&sh->lru) &&
!test_bit(STRIPE_HANDLE, &sh->state) &&
- atomic_read(&sh->count) == 0) {
+ refcount_read(&sh->count) == 0) {
r5c_flush_stripe(conf, sh);
if (count++ >= R5C_RECLAIM_STRIPE_GROUP)
break;
@@ -2650,7 +2650,7 @@ r5c_cache_data(struct r5l_log *log, struct stripe_head *sh,
* don't delay.
*/
clear_bit(STRIPE_DELAYED, &sh->state);
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);

mutex_lock(&log->io_mutex);
/* meta + data */
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 2ce23b0..30c96a8 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -296,7 +296,7 @@ static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
struct list_head *temp_inactive_list)
{
- if (atomic_dec_and_test(&sh->count))
+ if (refcount_dec_and_test(&sh->count))
do_release_stripe(conf, sh, temp_inactive_list);
}

@@ -388,7 +388,7 @@ void raid5_release_stripe(struct stripe_head *sh)

/* Avoid release_list until the last reference.
*/
- if (atomic_add_unless(&sh->count, -1, 1))
+ if (refcount_dec_not_one(&sh->count))
return;

if (unlikely(!conf->mddev->thread) ||
@@ -401,7 +401,7 @@ void raid5_release_stripe(struct stripe_head *sh)
slow_path:
local_irq_save(flags);
/* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
- if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
+ if (refcount_dec_and_lock(&sh->count, &conf->device_lock)) {
INIT_LIST_HEAD(&list);
hash = sh->hash_lock_index;
do_release_stripe(conf, sh, &list);
@@ -491,7 +491,7 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
struct r5conf *conf = sh->raid_conf;
int i, seq;

- BUG_ON(atomic_read(&sh->count) != 0);
+ BUG_ON(refcount_read(&sh->count) != 0);
BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
BUG_ON(stripe_operations_active(sh));
BUG_ON(sh->batch_head);
@@ -668,11 +668,11 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
&conf->cache_state);
} else {
init_stripe(sh, sector, previous);
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
}
- } else if (!atomic_inc_not_zero(&sh->count)) {
+ } else if (!refcount_inc_not_zero(&sh->count)) {
spin_lock(&conf->device_lock);
- if (!atomic_read(&sh->count)) {
+ if (!refcount_read(&sh->count)) {
if (!test_bit(STRIPE_HANDLE, &sh->state))
atomic_inc(&conf->active_stripes);
BUG_ON(list_empty(&sh->lru) &&
@@ -688,7 +688,7 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
sh->group = NULL;
}
}
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
spin_unlock(&conf->device_lock);
}
} while (sh == NULL);
@@ -752,9 +752,9 @@ static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh
hash = stripe_hash_locks_hash(head_sector);
spin_lock_irq(conf->hash_locks + hash);
head = __find_stripe(conf, head_sector, conf->generation);
- if (head && !atomic_inc_not_zero(&head->count)) {
+ if (head && !refcount_inc_not_zero(&head->count)) {
spin_lock(&conf->device_lock);
- if (!atomic_read(&head->count)) {
+ if (!refcount_read(&head->count)) {
if (!test_bit(STRIPE_HANDLE, &head->state))
atomic_inc(&conf->active_stripes);
BUG_ON(list_empty(&head->lru) &&
@@ -770,7 +770,7 @@ static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh
head->group = NULL;
}
}
- atomic_inc(&head->count);
+ refcount_inc(&head->count);
spin_unlock(&conf->device_lock);
}
spin_unlock_irq(conf->hash_locks + hash);
@@ -833,7 +833,7 @@ static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh
sh->batch_head->bm_seq = seq;
}

- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
unlock_out:
unlock_two_stripes(head, sh);
out:
@@ -1036,9 +1036,9 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
pr_debug("%s: for %llu schedule op %d on disc %d\n",
__func__, (unsigned long long)sh->sector,
bi->bi_opf, i);
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
if (sh != head_sh)
- atomic_inc(&head_sh->count);
+ refcount_inc(&head_sh->count);
if (use_new_offset(conf, sh))
bi->bi_iter.bi_sector = (sh->sector
+ rdev->new_data_offset);
@@ -1097,9 +1097,9 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
"replacement disc %d\n",
__func__, (unsigned long long)sh->sector,
rbi->bi_opf, i);
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
if (sh != head_sh)
- atomic_inc(&head_sh->count);
+ refcount_inc(&head_sh->count);
if (use_new_offset(conf, sh))
rbi->bi_iter.bi_sector = (sh->sector
+ rrdev->new_data_offset);
@@ -1275,7 +1275,7 @@ static void ops_run_biofill(struct stripe_head *sh)
}
}

- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
async_trigger_callback(&submit);
}
@@ -1353,7 +1353,7 @@ ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
if (i != target)
xor_srcs[count++] = sh->dev[i].page;

- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);

init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
@@ -1441,7 +1441,7 @@ ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
dest = tgt->page;

- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);

if (target == qd_idx) {
count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
@@ -1516,7 +1516,7 @@ ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
__func__, (unsigned long long)sh->sector, faila, failb);

- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);

if (failb == syndrome_disks+1) {
/* Q disk is one of the missing disks */
@@ -1784,7 +1784,7 @@ ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
break;
}
if (i >= sh->disks) {
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
set_bit(R5_Discard, &sh->dev[pd_idx].flags);
ops_complete_reconstruct(sh);
return;
@@ -1825,7 +1825,7 @@ ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
flags = ASYNC_TX_ACK |
(prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);

- atomic_inc(&head_sh->count);
+ refcount_inc(&head_sh->count);
init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
to_addr_conv(sh, percpu, j));
} else {
@@ -1867,7 +1867,7 @@ ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
break;
}
if (i >= sh->disks) {
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
ops_complete_reconstruct(sh);
@@ -1891,7 +1891,7 @@ ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
struct stripe_head, batch_list) == head_sh;

if (last_stripe) {
- atomic_inc(&head_sh->count);
+ refcount_inc(&head_sh->count);
init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
head_sh, to_addr_conv(sh, percpu, j));
} else
@@ -1948,7 +1948,7 @@ static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
&sh->ops.zero_sum_result, &submit);

- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
tx = async_trigger_callback(&submit);
}
@@ -1967,7 +1967,7 @@ static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu
if (!checkp)
srcs[count] = NULL;

- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
sh, to_addr_conv(sh, percpu, 0));
async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
@@ -2057,7 +2057,7 @@ static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
INIT_LIST_HEAD(&sh->lru);
INIT_LIST_HEAD(&sh->r5c);
INIT_LIST_HEAD(&sh->log_list);
- atomic_set(&sh->count, 1);
+ refcount_set(&sh->count, 1);
sh->log_start = MaxSector;
for (i = 0; i < disks; i++) {
struct r5dev *dev = &sh->dev[i];
@@ -2354,7 +2354,7 @@ static int drop_one_stripe(struct r5conf *conf)
spin_unlock_irq(conf->hash_locks + hash);
if (!sh)
return 0;
- BUG_ON(atomic_read(&sh->count));
+ BUG_ON(refcount_read(&sh->count));
shrink_buffers(sh);
kmem_cache_free(conf->slab_cache, sh);
atomic_dec(&conf->active_stripes);
@@ -2386,7 +2386,7 @@ static void raid5_end_read_request(struct bio * bi)
break;

pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
- (unsigned long long)sh->sector, i, atomic_read(&sh->count),
+ (unsigned long long)sh->sector, i, refcount_read(&sh->count),
bi->bi_error);
if (i == disks) {
bio_reset(bi);
@@ -2523,7 +2523,7 @@ static void raid5_end_write_request(struct bio *bi)
}
}
pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
- (unsigned long long)sh->sector, i, atomic_read(&sh->count),
+ (unsigned long long)sh->sector, i, refcount_read(&sh->count),
bi->bi_error);
if (i == disks) {
bio_reset(bi);
@@ -4545,7 +4545,7 @@ static void handle_stripe(struct stripe_head *sh)
pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
"pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
(unsigned long long)sh->sector, sh->state,
- atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
+ refcount_read(&sh->count), sh->pd_idx, sh->qd_idx,
sh->check_state, sh->reconstruct_state);

analyse_stripe(sh, &s);
@@ -4924,7 +4924,7 @@ static void activate_bit_delay(struct r5conf *conf,
struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
int hash;
list_del_init(&sh->lru);
- atomic_inc(&sh->count);
+ refcount_inc(&sh->count);
hash = sh->hash_lock_index;
__release_stripe(conf, sh, &temp_inactive_list[hash]);
}
@@ -5240,7 +5240,7 @@ static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
sh->group = NULL;
}
list_del_init(&sh->lru);
- BUG_ON(atomic_inc_return(&sh->count) != 1);
+ BUG_ON(refcount_inc_not_zero(&sh->count));
return sh;
}

diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 4bb27b9..a1ed351 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -3,6 +3,7 @@

#include <linux/raid/xor.h>
#include <linux/dmaengine.h>
+#include <linux/refcount.h>

/*
*
@@ -207,7 +208,7 @@ struct stripe_head {
short ddf_layout;/* use DDF ordering to calculate Q */
short hash_lock_index;
unsigned long state; /* state flags */
- atomic_t count; /* nr of active thread/requests */
+ refcount_t count; /* nr of active thread/requests */
int bm_seq; /* sequence number for bitmap flushes */
int disks; /* disks in stripe */
int overwrite_disks; /* total overwrite disks in stripe,
--
2.7.4