From 186debd6ede29da9d51cffdb93cadee66e4e1e23 Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Fri, 3 Mar 2017 10:55:23 +0200 Subject: [PATCH] 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 Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor Signed-off-by: David Sterba --- fs/btrfs/scrub.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index c9406bf302b8..d2c35848e61d 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -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; -- 2.20.1