[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20191104212149.127095645@linuxfoundation.org>
Date: Mon, 4 Nov 2019 22:45:13 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Yihui Zeng <yzeng56@....edu>,
Dan Carpenter <dan.carpenter@...cle.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>
Subject: [PATCH 5.3 123/163] s390/cmm: fix information leak in cmm_timeout_handler()
From: Yihui ZENG <yzeng56@....edu>
commit b8e51a6a9db94bc1fb18ae831b3dab106b5a4b5f upstream.
The problem is that we were putting the NUL terminator too far:
buf[sizeof(buf) - 1] = '\0';
If the user input isn't NUL terminated and they haven't initialized the
whole buffer then it leads to an info leak. The NUL terminator should
be:
buf[len - 1] = '\0';
Signed-off-by: Yihui Zeng <yzeng56@....edu>
Cc: stable@...r.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
[heiko.carstens@...ibm.com: keep semantics of how *lenp and *ppos are handled]
Signed-off-by: Heiko Carstens <heiko.carstens@...ibm.com>
Signed-off-by: Vasily Gorbik <gor@...ux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/s390/mm/cmm.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/arch/s390/mm/cmm.c
+++ b/arch/s390/mm/cmm.c
@@ -298,16 +298,16 @@ static int cmm_timeout_handler(struct ct
}
if (write) {
- len = *lenp;
- if (copy_from_user(buf, buffer,
- len > sizeof(buf) ? sizeof(buf) : len))
+ len = min(*lenp, sizeof(buf));
+ if (copy_from_user(buf, buffer, len))
return -EFAULT;
- buf[sizeof(buf) - 1] = '\0';
+ buf[len - 1] = '\0';
cmm_skip_blanks(buf, &p);
nr = simple_strtoul(p, &p, 0);
cmm_skip_blanks(p, &p);
seconds = simple_strtoul(p, &p, 0);
cmm_set_timeout(nr, seconds);
+ *ppos += *lenp;
} else {
len = sprintf(buf, "%ld %ld\n",
cmm_timeout_pages, cmm_timeout_seconds);
@@ -315,9 +315,9 @@ static int cmm_timeout_handler(struct ct
len = *lenp;
if (copy_to_user(buffer, buf, len))
return -EFAULT;
+ *lenp = len;
+ *ppos += len;
}
- *lenp = len;
- *ppos += len;
return 0;
}
Powered by blists - more mailing lists