From: Dan Carpenter <dan.carpenter@oracle.com> stable inclusion from linux-4.19.162 commit 304c080fc33258e3b177b6f0736b97d54e6fea3b CVE: CVE-2020-35519 -------------------------------- [ Upstream commit 6ee50c8e262a0f0693dad264c3c99e30e6442a56 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Reviewed-by: Yue Haibing <yuehaibing@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Cheng Jian <cj.chengjian@huawei.com> --- net/x25/af_x25.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index 20a511398389..86971df0baf6 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -680,7 +680,8 @@ 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; } @@ -770,7 +771,8 @@ 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; -- 2.25.1