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net, sctp: convert sctp_chunk.refcnt 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 S. Miller <davem@davemloft.net>
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Reshetova, Elena authored and David S. Miller committed Jul 4, 2017
1 parent c0acdfb commit e7f0279
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Showing 2 changed files with 4 additions and 4 deletions.
2 changes: 1 addition & 1 deletion include/net/sctp/structs.h
Original file line number Diff line number Diff line change
Expand Up @@ -524,7 +524,7 @@ int sctp_chunk_abandoned(struct sctp_chunk *);
struct sctp_chunk {
struct list_head list;

atomic_t refcnt;
refcount_t refcnt;

/* How many times this chunk have been sent, for prsctp RTX policy */
int sent_count;
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6 changes: 3 additions & 3 deletions net/sctp/sm_make_chunk.c
Original file line number Diff line number Diff line change
Expand Up @@ -1345,7 +1345,7 @@ struct sctp_chunk *sctp_chunkify(struct sk_buff *skb,
INIT_LIST_HEAD(&retval->transmitted_list);
INIT_LIST_HEAD(&retval->frag_list);
SCTP_DBG_OBJCNT_INC(chunk);
atomic_set(&retval->refcnt, 1);
refcount_set(&retval->refcnt, 1);

nodata:
return retval;
Expand Down Expand Up @@ -1458,13 +1458,13 @@ void sctp_chunk_free(struct sctp_chunk *chunk)
/* Grab a reference to the chunk. */
void sctp_chunk_hold(struct sctp_chunk *ch)
{
atomic_inc(&ch->refcnt);
refcount_inc(&ch->refcnt);
}

/* Release a reference to the chunk. */
void sctp_chunk_put(struct sctp_chunk *ch)
{
if (atomic_dec_and_test(&ch->refcnt))
if (refcount_dec_and_test(&ch->refcnt))
sctp_chunk_destroy(ch);
}

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