Commit 4c355cdf authored by Reshetova, Elena's avatar Reshetova, Elena Committed by David S. Miller

net: convert sk_filter.refcnt 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>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 726bceca
......@@ -7,6 +7,7 @@
#include <stdarg.h>
#include <linux/atomic.h>
#include <linux/refcount.h>
#include <linux/compat.h>
#include <linux/skbuff.h>
#include <linux/linkage.h>
......@@ -430,7 +431,7 @@ struct bpf_prog {
};
struct sk_filter {
atomic_t refcnt;
refcount_t refcnt;
struct rcu_head rcu;
struct bpf_prog *prog;
};
......
......@@ -928,7 +928,7 @@ static void sk_filter_release_rcu(struct rcu_head *rcu)
*/
static void sk_filter_release(struct sk_filter *fp)
{
if (atomic_dec_and_test(&fp->refcnt))
if (refcount_dec_and_test(&fp->refcnt))
call_rcu(&fp->rcu, sk_filter_release_rcu);
}
......@@ -943,20 +943,27 @@ void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp)
/* try to charge the socket memory if there is space available
* return true on success
*/
bool sk_filter_charge(struct sock *sk, struct sk_filter *fp)
static bool __sk_filter_charge(struct sock *sk, struct sk_filter *fp)
{
u32 filter_size = bpf_prog_size(fp->prog->len);
/* same check as in sock_kmalloc() */
if (filter_size <= sysctl_optmem_max &&
atomic_read(&sk->sk_omem_alloc) + filter_size < sysctl_optmem_max) {
atomic_inc(&fp->refcnt);
atomic_add(filter_size, &sk->sk_omem_alloc);
return true;
}
return false;
}
bool sk_filter_charge(struct sock *sk, struct sk_filter *fp)
{
bool ret = __sk_filter_charge(sk, fp);
if (ret)
refcount_inc(&fp->refcnt);
return ret;
}
static struct bpf_prog *bpf_migrate_filter(struct bpf_prog *fp)
{
struct sock_filter *old_prog;
......@@ -1179,12 +1186,12 @@ static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk)
return -ENOMEM;
fp->prog = prog;
atomic_set(&fp->refcnt, 0);
if (!sk_filter_charge(sk, fp)) {
if (!__sk_filter_charge(sk, fp)) {
kfree(fp);
return -ENOMEM;
}
refcount_set(&fp->refcnt, 1);
old_fp = rcu_dereference_protected(sk->sk_filter,
lockdep_sock_is_held(sk));
......
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