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Commit 0029c0de authored by Reshetova, Elena's avatar Reshetova, Elena Committed by David S. Miller
Browse files

net, ipv4: convert fib_info.fib_clntref 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: default avatarElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: default avatarHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDavid Windsor <dwindsor@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f6a6fede

include/net/ip_fib.h

+4 −3
Original line number Diff line number Diff line
@@ -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);

}

net/ipv4/fib_semantics.c

+1 −1
Original line number Diff line number Diff line
@@ -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)]);

net/ipv4/fib_trie.c

+1 −1
Original line number Diff line number Diff line
@@ -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;