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btrfs: convert scrub_block.refs from atomic_t to refcount_t 

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@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Elena Reshetova 2017-03-03 10:55:23 +02:00 committed by David Sterba
parent 6f615018b3
commit 186debd6ed
1 changed files with 5 additions and 5 deletions
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10
fs/btrfs/scrub.c
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@ -112,7 +112,7 @@ struct scrub_block {
struct scrub_page *pagev[SCRUB_MAX_PAGES_PER_BLOCK];
int page_count;
atomic_t outstanding_pages;
atomic_t refs; /* free mem on transition to zero */
refcount_t refs; /* free mem on transition to zero */
struct scrub_ctx *sctx;
struct scrub_parity *sparity;
struct {
@ -1998,12 +1998,12 @@ static int scrub_checksum_super(struct scrub_block *sblock)
static void scrub_block_get(struct scrub_block *sblock)
{
atomic_inc(&sblock->refs);
refcount_inc(&sblock->refs);
}
static void scrub_block_put(struct scrub_block *sblock)
{
if (atomic_dec_and_test(&sblock->refs)) {
if (refcount_dec_and_test(&sblock->refs)) {
int i;
if (sblock->sparity)
@ -2255,7 +2255,7 @@ static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
/* one ref inside this function, plus one for each page added to
* a bio later on */
atomic_set(&sblock->refs, 1);
refcount_set(&sblock->refs, 1);
sblock->sctx = sctx;
sblock->no_io_error_seen = 1;
@ -2555,7 +2555,7 @@ static int scrub_pages_for_parity(struct scrub_parity *sparity,
/* one ref inside this function, plus one for each page added to
* a bio later on */
atomic_set(&sblock->refs, 1);
refcount_set(&sblock->refs, 1);
sblock->sctx = sctx;
sblock->no_io_error_seen = 1;
sblock->sparity = sparity;