From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Tue, 1 Dec 2020 18:15:12 +0300
Subject: net/x25: prevent a couple of overflows
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Patch-mainline: v5.10-rc7
Git-commit: 6ee50c8e262a0f0693dad264c3c99e30e6442a56
References: bsc#1178590 CVE-2020-35519 bsc#1183696
The .x25_addr[] address comes from the user and is not necessarily
NUL terminated. This leads to a couple problems. The first problem is
that the strlen() in x25_bind() can read beyond the end of the buffer.
The second problem is more subtle and could result in memory corruption.
The call tree is:
x25_connect()
--> x25_write_internal()
--> x25_addr_aton()
The .x25_addr[] buffers are copied to the "addresses" buffer from
x25_write_internal() so it will lead to stack corruption.
Verify that the strings are NUL terminated and return -EINVAL if they
are not.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Fixes: a9288525d2ae ("X25: Dont let x25_bind use addresses containing characters")
Reported-by: "kiyin(尹亮)" <kiyin@tencent.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Martin Schiller <ms@dev.tdt.de>
Link: https://lore.kernel.org/r/X8ZeAKm8FnFpN//B@mwanda
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Michal Kubecek <mkubecek@suse.cz>
---
net/x25/af_x25.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -675,7 +675,8 @@ static int x25_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
int len, i, rc = 0;
if (addr_len != sizeof(struct sockaddr_x25) ||
- addr->sx25_family != AF_X25) {
+ addr->sx25_family != AF_X25 ||
+ strnlen(addr->sx25_addr.x25_addr, X25_ADDR_LEN) == X25_ADDR_LEN) {
rc = -EINVAL;
goto out;
}
@@ -765,7 +766,8 @@ static int x25_connect(struct socket *sock, struct sockaddr *uaddr,
rc = -EINVAL;
if (addr_len != sizeof(struct sockaddr_x25) ||
- addr->sx25_family != AF_X25)
+ addr->sx25_family != AF_X25 ||
+ strnlen(addr->sx25_addr.x25_addr, X25_ADDR_LEN) == X25_ADDR_LEN)
goto out;
rc = -ENETUNREACH;