| Date | Mon, 12 May 2014 02:33:37 +0200 | From | Willy Tarreau <> | Subject | [ 097/143] net: llc: fix use after free in llc_ui_recvmsg |
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2.6.32-longterm review patch. If anyone has any objections, please let me know.
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From: Daniel Borkmann <dborkman@redhat.com>
[ Upstream commit 4d231b76eef6c4a6bd9c96769e191517765942cb ]
While commit 30a584d944fb fixes datagram interface in LLC, a use after free bug has been introduced for SOCK_STREAM sockets that do not make use of MSG_PEEK.
The flow is as follow ...
if (!(flags & MSG_PEEK)) { ... sk_eat_skb(sk, skb, false); ... } ... if (used + offset < skb->len) continue;
... where sk_eat_skb() calls __kfree_skb(). Therefore, cache original length and work on skb_len to check partial reads.
Fixes: 30a584d944fb ("[LLX]: SOCK_DGRAM interface fixes") Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Cc: Stephen Hemminger <stephen@networkplumber.org> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Willy Tarreau <w@1wt.eu> --- net/llc/af_llc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c index 606b6ad..f62b63e 100644 --- a/net/llc/af_llc.c +++ b/net/llc/af_llc.c @@ -669,7 +669,7 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock, struct llc_sock *llc = llc_sk(sk); size_t copied = 0; u32 peek_seq = 0; - u32 *seq; + u32 *seq, skb_len; unsigned long used; int target; /* Read at least this many bytes */ long timeo; @@ -767,6 +767,7 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock, } continue; found_ok_skb: + skb_len = skb->len; /* Ok so how much can we use? */ used = skb->len - offset; if (len < used) @@ -797,7 +798,7 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock, goto copy_uaddr; /* Partial read */ - if (used + offset < skb->len) + if (used + offset < skb_len) continue; } while (len > 0); -- 1.7.12.2.21.g234cd45.dirty
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