This is a note to let you know that I've just added the patch titled
net: Fix skb_set_peeked use-after-free bug
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-fix-skb_set_peeked-use-after-free-bug.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From foo@baz Sat Sep 26 11:19:08 PDT 2015
From: Herbert Xu <[email protected]>
Date: Tue, 4 Aug 2015 15:42:47 +0800
Subject: net: Fix skb_set_peeked use-after-free bug
From: Herbert Xu <[email protected]>
[ 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 <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
Tested-by: Brenden Blanco <[email protected]>
Reviewed-by: Konstantin Khlebnikov <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
net/core/datagram.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -130,12 +130,12 @@ 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))
@@ -143,7 +143,7 @@ static int skb_set_peeked(struct sk_buff
nskb = skb_clone(skb, GFP_ATOMIC);
if (!nskb)
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);
skb->prev->next = nskb;
skb->next->prev = nskb;
@@ -156,7 +156,7 @@ static int skb_set_peeked(struct sk_buff
done:
skb->peeked = 1;
- return 0;
+ return skb;
}
/**
@@ -228,8 +228,9 @@ struct sk_buff *__skb_recv_datagram(stru
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);
Patches currently in stable-queue which might be from
[email protected] are
queue-3.14/net-fix-skb_set_peeked-use-after-free-bug.patch
queue-3.14/ipv6-lock-socket-in-ip6_datagram_connect.patch
queue-3.14/net-fix-skb-csum-races-when-peeking.patch
queue-3.14/net-clone-skb-before-setting-peeked-flag.patch
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