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net, ipv4: convert fib_info.fib_clntref 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>
This commit is contained in:
Reshetova, Elena 2017-07-04 09:35:02 +03:00 committed by David S. Miller
parent f6a6fede28
commit 0029c0deb5
3 changed files with 6 additions and 5 deletions
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7
include/net/ip_fib.h
View File

@ -23,6 +23,7 @@
#include <net/inetpeer.h> #include <net/inetpeer.h>
#include <linux/percpu.h> #include <linux/percpu.h>
#include <linux/notifier.h> #include <linux/notifier.h>
#include <linux/refcount.h>
struct fib_config { struct fib_config {
u8 fc_dst_len; u8 fc_dst_len;
@ -105,7 +106,7 @@ struct fib_info {
struct hlist_node fib_lhash; struct hlist_node fib_lhash;
struct net *fib_net; struct net *fib_net;
int fib_treeref; int fib_treeref;
atomic_t fib_clntref; refcount_t fib_clntref;
unsigned int fib_flags; unsigned int fib_flags;
unsigned char fib_dead; unsigned char fib_dead;
unsigned char fib_protocol; 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) 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) 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); free_fib_info(fi);
} }

2
net/ipv4/fib_semantics.c
View File

@ -1253,7 +1253,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
} }
fi->fib_treeref++; fi->fib_treeref++;
atomic_inc(&fi->fib_clntref); refcount_set(&fi->fib_clntref, 1);
spin_lock_bh(&fib_info_lock); spin_lock_bh(&fib_info_lock);
hlist_add_head(&fi->fib_hash, hlist_add_head(&fi->fib_hash,
&fib_info_hash[fib_info_hashfn(fi)]); &fib_info_hash[fib_info_hashfn(fi)]);

2
net/ipv4/fib_trie.c
View File

@ -1463,7 +1463,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
} }
if (!(fib_flags & FIB_LOOKUP_NOREF)) if (!(fib_flags & FIB_LOOKUP_NOREF))
atomic_inc(&fi->fib_clntref); refcount_inc(&fi->fib_clntref);
res->prefix = htonl(n->key); res->prefix = htonl(n->key);
res->prefixlen = KEYLENGTH - fa->fa_slen; res->prefixlen = KEYLENGTH - fa->fa_slen;