Commit 6ee50c8e authored Dec 01, 2020 by Dan Carpenter Committed by Jakub Kicinski Dec 02, 2020

net/x25: prevent a couple of overflows



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: 1da177e4 ("Linux-2.6.12-rc2")
Fixes: a9288525 ("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>

parent 07500a60

net/x25/af_x25.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -681,7 +681,8 @@ 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;
		}
		@@ -775,7 +776,8 @@ 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;

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