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btrfs: convert scrub_ctx.refs from atomic_t to refcount_t

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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 10:55:25 +02:00 committed by David Sterba
parent 78a764504d
commit 99f4cdb16f
1 changed files with 5 additions and 5 deletions
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10
fs/btrfs/scrub.c
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@ -202,7 +202,7 @@ struct scrub_ctx {
* doesn't free the scrub context before or while the workers are
* doing the wakeup() call.
*/
atomic_t refs;
refcount_t refs;
};
struct scrub_fixup_nodatasum {
@ -305,7 +305,7 @@ static void scrub_put_ctx(struct scrub_ctx *sctx);
static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
{
atomic_inc(&sctx->refs);
refcount_inc(&sctx->refs);
atomic_inc(&sctx->bios_in_flight);
}
@ -356,7 +356,7 @@ static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
{
struct btrfs_fs_info *fs_info = sctx->fs_info;
atomic_inc(&sctx->refs);
refcount_inc(&sctx->refs);
/*
* increment scrubs_running to prevent cancel requests from
* completing as long as a worker is running. we must also
@ -447,7 +447,7 @@ static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
static void scrub_put_ctx(struct scrub_ctx *sctx)
{
if (atomic_dec_and_test(&sctx->refs))
if (refcount_dec_and_test(&sctx->refs))
scrub_free_ctx(sctx);
}
@ -462,7 +462,7 @@ struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
sctx = kzalloc(sizeof(*sctx), GFP_KERNEL);
if (!sctx)
goto nomem;
atomic_set(&sctx->refs, 1);
refcount_set(&sctx->refs, 1);
sctx->is_dev_replace = is_dev_replace;
sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
sctx->curr = -1;