From: Peilin Ye <yepeilin.cs@gmail.com>
To: Joerg Reuter <jreuter@yaina.de>, Ralf Baechle <ralf@linux-mips.org>
Cc: Peilin Ye <yepeilin.cs@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
syzkaller-bugs@googlegroups.com,
linux-kernel-mentees@lists.linuxfoundation.org,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
linux-hams@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [Linux-kernel-mentees] [PATCH net] AX.25: Fix out-of-bounds read in ax25_connect()
Date: Wed, 22 Jul 2020 11:19:01 -0400 [thread overview]
Message-ID: <20200722151901.350003-1-yepeilin.cs@gmail.com> (raw)
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>
---
net/ax25/af_ax25.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index fd91cd34f25e..ef5bf116157a 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1187,7 +1187,9 @@ static int __must_check ax25_connect(struct socket *sock,
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;
}
--
2.25.1
next reply other threads:[~2020-07-22 15:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-22 15:19 Peilin Ye [this message]
2020-07-23 0:57 ` [Linux-kernel-mentees] [PATCH net] AX.25: Fix out-of-bounds read in ax25_connect() David Miller
2020-07-23 15:15 ` Peilin Ye
2020-07-23 14:28 ` Dan Carpenter
2020-07-23 15:13 ` Peilin Ye
2020-07-23 15:50 ` Dan Carpenter
2020-07-23 16:43 ` Peilin Ye
2020-07-23 21:41 ` vk2tv
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