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.reshet...@intel.com> Signed-off-by: Hans Liljestrand <ishkam...@gmail.com> Signed-off-by: Kees Cook <keesc...@chromium.org> Signed-off-by: David Windsor <dwind...@gmail.com> --- include/net/ip_fib.h | 7 ++++--- net/ipv4/fib_semantics.c | 2 +- net/ipv4/fib_trie.c | 2 +- 3 files changed, 6 insertions(+), 5 deletions(-) diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h index 3dbfd5e..41d580c 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -23,6 +23,7 @@ #include <net/inetpeer.h> #include <linux/percpu.h> #include <linux/notifier.h> +#include <linux/refcount.h> struct fib_config { u8 fc_dst_len; @@ -105,7 +106,7 @@ struct fib_info { struct hlist_node fib_lhash; struct net *fib_net; int fib_treeref; - atomic_t fib_clntref; + refcount_t fib_clntref; unsigned int fib_flags; unsigned char fib_dead; unsigned char fib_protocol; @@ -430,12 +431,12 @@ void free_fib_info(struct fib_info *fi); static inline void fib_info_hold(struct fib_info *fi) { - atomic_inc(&fi->fib_clntref); + refcount_inc(&fi->fib_clntref); } static inline void fib_info_put(struct fib_info *fi) { - if (atomic_dec_and_test(&fi->fib_clntref)) + if (refcount_dec_and_test(&fi->fib_clntref)) free_fib_info(fi); } diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index ff47ea1..22210010 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -1253,7 +1253,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg, } fi->fib_treeref++; - atomic_inc(&fi->fib_clntref); + refcount_set(&fi->fib_clntref, 1); spin_lock_bh(&fib_info_lock); hlist_add_head(&fi->fib_hash, &fib_info_hash[fib_info_hashfn(fi)]); diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index d56659e..64668c6 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -1463,7 +1463,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp, } if (!(fib_flags & FIB_LOOKUP_NOREF)) - atomic_inc(&fi->fib_clntref); + refcount_inc(&fi->fib_clntref); res->prefix = htonl(n->key); res->prefixlen = KEYLENGTH - fa->fa_slen; -- 2.7.4