[34-longterm 232/247] net: ax25: fix information leak to userland

From: Paul Gortmaker
Date: Thu Jun 23 2011 - 13:45:57 EST

From: Vasiliy Kulikov <segooon@xxxxxxxxx>

This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.

commit fe10ae53384e48c51996941b7720ee16995cbcb7 upstream.

Sometimes ax25_getname() doesn't initialize all members of fsa_digipeater
field of fsa struct, also the struct has padding bytes between
sax25_call and sax25_ndigis fields. This structure is then copied to
userland. It leads to leaking of contents of kernel stack memory.

Signed-off-by: Vasiliy Kulikov <segooon@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
net/ax25/af_ax25.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index 65c5801..eb100ce 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1392,6 +1392,7 @@ static int ax25_getname(struct socket *sock, struct sockaddr *uaddr,
ax25_cb *ax25;
int err = 0;

+ memset(fsa, 0, sizeof(fsa));
ax25 = ax25_sk(sk);

@@ -1403,7 +1404,6 @@ static int ax25_getname(struct socket *sock, struct sockaddr *uaddr,

fsa->fsa_ax25.sax25_family = AF_AX25;
fsa->fsa_ax25.sax25_call = ax25->dest_addr;
- fsa->fsa_ax25.sax25_ndigis = 0;

if (ax25->digipeat != NULL) {
ndigi = ax25->digipeat->ndigi;

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