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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	syzbot+c82752228ed975b0a623@syzkaller.appspotmail.com,
	Peilin Ye <yepeilin.cs@gmail.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.19 01/17] AX.25: Fix out-of-bounds read in ax25_connect()
Date: Thu, 30 Jul 2020 10:04:27 +0200
Message-ID: <20200730074420.528010553@linuxfoundation.org> (raw)
In-Reply-To: <20200730074420.449233408@linuxfoundation.org>

From: Peilin Ye <yepeilin.cs@gmail.com>

[ Upstream commit 2f2a7ffad5c6cbf3d438e813cfdc88230e185ba6 ]

Checks on `addr_len` and `fsa->fsa_ax25.sax25_ndigis` are insufficient.
ax25_connect() can go out of bounds when `fsa->fsa_ax25.sax25_ndigis`
equals to 7 or 8. Fix it.

This issue has been reported as a KMSAN uninit-value bug, because in such
a case, ax25_connect() reaches into the uninitialized portion of the
`struct sockaddr_storage` statically allocated in __sys_connect().

It is safe to remove `fsa->fsa_ax25.sax25_ndigis > AX25_MAX_DIGIS` because
`addr_len` is guaranteed to be less than or equal to
`sizeof(struct full_sockaddr_ax25)`.

Reported-by: syzbot+c82752228ed975b0a623@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=55ef9d629f3b3d7d70b69558015b63b48d01af66
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ax25/af_ax25.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1190,7 +1190,9 @@ static int __must_check ax25_connect(str
 	if (addr_len > sizeof(struct sockaddr_ax25) &&
 	    fsa->fsa_ax25.sax25_ndigis != 0) {
 		/* Valid number of digipeaters ? */
-		if (fsa->fsa_ax25.sax25_ndigis < 1 || fsa->fsa_ax25.sax25_ndigis > AX25_MAX_DIGIS) {
+		if (fsa->fsa_ax25.sax25_ndigis < 1 ||
+		    addr_len < sizeof(struct sockaddr_ax25) +
+		    sizeof(ax25_address) * fsa->fsa_ax25.sax25_ndigis) {
 			err = -EINVAL;
 			goto out_release;
 		}



  reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-30  8:04 [PATCH 4.19 00/17] 4.19.136-rc1 review Greg Kroah-Hartman
2020-07-30  8:04 ` Greg Kroah-Hartman [this message]
2020-07-30  8:04 ` [PATCH 4.19 02/17] AX.25: Prevent out-of-bounds read in ax25_sendmsg() Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 03/17] dev: Defer free of skbs in flush_backlog Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 04/17] drivers/net/wan/x25_asy: Fix to make it work Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 05/17] ip6_gre: fix null-ptr-deref in ip6gre_init_net() Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 06/17] net-sysfs: add a newline when printing tx_timeout by sysfs Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 07/17] net: udp: Fix wrong clean up for IS_UDPLITE macro Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 08/17] qrtr: orphan socket in qrtr_release() Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 09/17] rxrpc: Fix sendmsg() returning EPIPE due to recvmsg() returning ENODATA Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 10/17] tcp: allow at most one TLP probe per flight Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 11/17] AX.25: Prevent integer overflows in connect and sendmsg Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 12/17] sctp: shrink stream outq only when new outcnt < old outcnt Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 13/17] sctp: shrink stream outq when fails to do addstream reconf Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 14/17] udp: Copy has_conns in reuseport_grow() Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 15/17] udp: Improve load balancing for SO_REUSEPORT Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 16/17] rtnetlink: Fix memory(net_device) leak when ->newlink fails Greg Kroah-Hartman
2020-07-30  8:04 ` [PATCH 4.19 17/17] regmap: debugfs: check count when read regmap file Greg Kroah-Hartman
2020-07-30 16:47 ` [PATCH 4.19 00/17] 4.19.136-rc1 review Guenter Roeck
2020-07-31 12:00 ` Naresh Kamboju
2020-07-31 12:52 ` Jon Hunter

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