diff options
| author | Herbert Xu <herbert@gondor.apana.org.au> | 2015-08-04 15:42:47 +0800 |
|---|---|---|
| committer | Willy Tarreau <w@1wt.eu> | 2015-12-06 00:49:06 +0100 |
| commit | f7152084ca7b1d225a85ade000dcb530d5cecfd0 (patch) | |
| tree | 9f41e06df8dff95b4dd7c43445783fec2cc42b12 | |
| parent | 52501955df29e42b29d4e8dea6b3c4332adccdd6 (diff) | |
net: Fix skb_set_peeked use-after-free bug
commit a0a2a6602496a45ae838a96db8b8173794b5d398 upstream.
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
(cherry picked from commit e553622ccb6b6e06079f980f55cf04128db3420c)
Signed-off-by: Willy Tarreau <w@1wt.eu>
| -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 cbb3100c37dc..c855336b3ebb 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -127,12 +127,12 @@ 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)) @@ -140,7 +140,7 @@ 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; @@ -153,7 +153,7 @@ static int skb_set_peeked(struct sk_buff *skb) done: skb->peeked = 1; - return 0; + return skb; } /** @@ -214,8 +214,9 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags, *peeked = skb->peeked; if (flags & MSG_PEEK) { - 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); |