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Date: Mon, 13 Jan 2014 16:27:58 -0800 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Daniel Borkmann <dborkman@...hat.com>, Stephen Hemminger <stephen@...workplumber.org>, Arnaldo Carvalho de Melo <acme@...stprotocols.net>, "David S. Miller" <davem@...emloft.net> Subject: [PATCH 3.12 37/77] net: llc: fix use after free in llc_ui_recvmsg 3.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann <dborkman@...hat.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@...hat.com> Cc: Stephen Hemminger <stephen@...workplumber.org> Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net> Signed-off-by: David S. Miller <davem@...emloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- net/llc/af_llc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/net/llc/af_llc.c +++ b/net/llc/af_llc.c @@ -715,7 +715,7 @@ static int llc_ui_recvmsg(struct kiocb * unsigned long cpu_flags; 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; @@ -812,6 +812,7 @@ static int llc_ui_recvmsg(struct kiocb * } continue; found_ok_skb: + skb_len = skb->len; /* Ok so how much can we use? */ used = skb->len - offset; if (len < used) @@ -844,7 +845,7 @@ static int llc_ui_recvmsg(struct kiocb * } /* Partial read */ - if (used + offset < skb->len) + if (used + offset < skb_len) continue; } while (len > 0); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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