xfrm: prevent ipcomp scratch buffer race condition

[karo-tx-linux.git] / net / xfrm / xfrm_ipcomp.c

diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index 2906d520eea7c2b7636fc94f3a60f5131701f57d..3be02b680268d1ccb7e3672a92777b12963b8562 100644 (file)
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -141,14 +141,14 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
        const int plen = skb->len;
        int dlen = IPCOMP_SCRATCH_SIZE;
        u8 *start = skb->data;
-       const int cpu = get_cpu();
-       u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
-       struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
+       struct crypto_comp *tfm;
+       u8 *scratch;
        int err;
 
        local_bh_disable();
+       scratch = *this_cpu_ptr(ipcomp_scratches);
+       tfm = *this_cpu_ptr(ipcd->tfms);
        err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
-       local_bh_enable();
        if (err)
                goto out;
 
@@ -158,13 +158,13 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
        }
 
        memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
-       put_cpu();
+       local_bh_enable();
 
        pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
        return 0;
 
 out:
-       put_cpu();
+       local_bh_enable();
        return err;
 }