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authorHerbert Xu <herbert@gondor.apana.org.au>2015-08-04 15:42:47 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-01 12:07:36 +0200
commit5fa39f16036eb627fe50a38c307fa99eace26ee3 (patch)
tree0b0f7a7ad88a8a871911e7c5a000ccf038981a87
parent4164cda8cad7303614d211192d27a912de53a463 (diff)
downloadlinux-linaro-stable-5fa39f16036eb627fe50a38c307fa99eace26ee3.tar.gz
net: Fix skb_set_peeked use-after-free bug
[ Upstream commit a0a2a6602496a45ae838a96db8b8173794b5d398 ] 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/core/datagram.c13
1 files changed, 7 insertions, 6 deletions
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 80b0fd83fac8..052b71c5b1b4 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -128,12 +128,12 @@ 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))
@@ -141,7 +141,7 @@ 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;
@@ -154,7 +154,7 @@ static int skb_set_peeked(struct sk_buff *skb)
done:
skb->peeked = 1;
- return 0;
+ return skb;
}
/**
@@ -226,8 +226,9 @@ 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);