diff options
| author | Herbert Xu <herbert@gondor.apana.org.au> | 2015-08-04 15:42:47 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-08-06 21:55:47 -0700 |
| commit | a0a2a6602496a45ae838a96db8b8173794b5d398 (patch) | |
| tree | 5508d9f02066c30854b0c88b82fffc03c857adef /net/core | |
| parent | 14d2b7c1a96ef37eb571599c73d4a1a606b964d6 (diff) | |
net: Fix skb_set_peeked use-after-free bug
The commit 738ac1ebb96d02e0d23bc320302a6ea94c612dec ("net: Clone
skb before setting peeked flag") introduced a use-after-free bug
in skb_recv_datagram. This is because skb_set_peeked may create
a new skb and free the existing one. As it stands the caller will
continue to use the old freed skb.
This patch fixes it by making skb_set_peeked return the new skb
(or the old one if unchanged).
Fixes: 738ac1ebb96d ("net: Clone skb before setting peeked flag")
Reported-by: Brenden Blanco <bblanco@plumgrid.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Brenden Blanco <bblanco@plumgrid.com>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/datagram.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/net/core/datagram.c b/net/core/datagram.c index 4967262b2707..617088aee21d 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -131,12 +131,12 @@ out_noerr: goto out; } -static int skb_set_peeked(struct sk_buff *skb) +static struct sk_buff *skb_set_peeked(struct sk_buff *skb) { struct sk_buff *nskb; if (skb->peeked) - return 0; + return skb; /* We have to unshare an skb before modifying it. */ if (!skb_shared(skb)) @@ -144,7 +144,7 @@ static int skb_set_peeked(struct sk_buff *skb) nskb = skb_clone(skb, GFP_ATOMIC); if (!nskb) - return -ENOMEM; + return ERR_PTR(-ENOMEM); skb->prev->next = nskb; skb->next->prev = nskb; @@ -157,7 +157,7 @@ static int skb_set_peeked(struct sk_buff *skb) done: skb->peeked = 1; - return 0; + return skb; } /** @@ -229,8 +229,9 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, continue; } - error = skb_set_peeked(skb); - if (error) + skb = skb_set_peeked(skb); + error = PTR_ERR(skb); + if (IS_ERR(skb)) goto unlock_err; atomic_inc(&skb->users); |