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authorDaniel Borkmann <dborkman@redhat.com>2013-12-30 22:40:50 (GMT)
committerDavid S. Miller <davem@davemloft.net>2014-01-03 00:31:09 (GMT)
commit4d231b76eef6c4a6bd9c96769e191517765942cb (patch)
treeae855d6ce8a7d2c67f13e2ab9f9376dc6b2e315d /net/llc
parent6cd4ce0099da7702f885b6fa9ebb49e3831d90b4 (diff)
net: llc: fix use after free in llc_ui_recvmsg
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>
Diffstat (limited to 'net/llc')
-rw-r--r--net/llc/af_llc.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 7b01b9f..c71b699 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -715,7 +715,7 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock,
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 *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)
@@ -844,7 +845,7 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock,
}
/* Partial read */
- if (used + offset < skb->len)
+ if (used + offset < skb_len)
continue;
} while (len > 0);

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