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Groups > linux.kernel > #1591808

[PATCH 14/17] fs, btrfs: convert scrub_block.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>
---
 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 8299f64..08895d8 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;
-- 
2.7.4

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[PATCH 00/17] fs, btrfs refcount conversions Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:00 +0100
  [PATCH 15/17] fs, btrfs: convert scrub_parity.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:10 +0100
  [PATCH 16/17] fs, btrfs: convert scrub_ctx.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:10 +0100
  [PATCH 10/17] fs, btrfs: convert extent_state.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:10 +0100
  [PATCH 05/17] fs, btrfs: convert btrfs_caching_control.count from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:10 +0100
  [PATCH 03/17] fs, btrfs: convert extent_map.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:10 +0100
  [PATCH 04/17] fs, btrfs: convert btrfs_ordered_extent.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:10 +0100
  [PATCH 09/17] fs, btrfs: convert btrfs_root.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:10 +0100
  [PATCH 17/17] fs, btrfs: convert btrfs_raid_bio.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:10 +0100
  [PATCH 08/17] fs, btrfs: convert btrfs_delayed_item.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 10:30 +0100
  [PATCH 14/17] fs, btrfs: convert scrub_block.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 11:00 +0100
  [PATCH 13/17] fs, btrfs: convert scrub_page.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 11:00 +0100
  [PATCH 11/17] fs, btrfs: convert compressed_bio.pending_bios from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 11:40 +0100
  [PATCH 06/17] fs, btrfs: convert btrfs_delayed_ref_node.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 13:40 +0100
  [PATCH 12/17] fs, btrfs: convert scrub_recover.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 14:00 +0100
  [PATCH 07/17] fs, btrfs: convert btrfs_delayed_node.refs from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-03 16:40 +0100
  Re: [PATCH 00/17] fs, btrfs refcount conversions Qu Wenruo <quwenruo@cn.fujitsu.com> - 2017-03-06 01:30 +0100
  Re: [PATCH 00/17] fs, btrfs refcount conversions Qu Wenruo <quwenruo@cn.fujitsu.com> - 2017-03-06 05:10 +0100
    Re: [PATCH 00/17] fs, btrfs refcount conversions Qu Wenruo <quwenruo@cn.fujitsu.com> - 2017-03-07 07:30 +0100
      RE: [PATCH 00/17] fs, btrfs refcount conversions "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-07 09:00 +0100
        Re: [PATCH 00/17] fs, btrfs refcount conversions David Sterba <dsterba@suse.cz> - 2017-03-09 16:40 +0100
  Re: [PATCH 00/17] fs, btrfs refcount conversions David Sterba <dsterba@suse.cz> - 2017-03-09 17:30 +0100
    RE: [PATCH 00/17] fs, btrfs refcount conversions "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-13 12:00 +0100

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