bio: Fix potential memory leak in bio_find_or_create_slab()

Do not leak memory by updating pointer with potentially NULL realloc return value.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/bio.c b/fs/bio.c
index 73922abba832d0a41c1cb01bbf5bcc0fec1cb78b..fed1f799cb56b1b251249e8f1d6316d1c40c50c6 100644 (file)
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -73,7 +73,7 @@ static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
 {
        unsigned int sz = sizeof(struct bio) + extra_size;
        struct kmem_cache *slab = NULL;
-       struct bio_slab *bslab;
+       struct bio_slab *bslab, *new_bio_slabs;
        unsigned int i, entry = -1;
 
        mutex_lock(&bio_slab_lock);
@@ -97,11 +97,12 @@ static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
 
        if (bio_slab_nr == bio_slab_max && entry == -1) {
                bio_slab_max <<= 1;
-               bio_slabs = krealloc(bio_slabs,
-                                    bio_slab_max * sizeof(struct bio_slab),
-                                    GFP_KERNEL);
-               if (!bio_slabs)
+               new_bio_slabs = krealloc(bio_slabs,
+                                        bio_slab_max * sizeof(struct bio_slab),
+                                        GFP_KERNEL);
+               if (!new_bio_slabs)
                        goto out_unlock;
+               bio_slabs = new_bio_slabs;
        }
        if (entry == -1)
                entry = bio_slab_nr++;