diff options
author | Yihui ZENG <yzeng56@asu.edu> | 2019-10-25 12:31:48 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-06 12:09:21 +0100 |
commit | 1cdb53607683a4fa8625a3f3eb65e5d9f4572166 (patch) | |
tree | 332c38ec0ddd5c541e091af6abcfbacd10c5db77 /arch/s390/mm | |
parent | 3af30fce8990fbe190831bdba55e4d2c97b7e222 (diff) |
s390/cmm: fix information leak in cmm_timeout_handler()
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@asu.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
[heiko.carstens@de.ibm.com: keep semantics of how *lenp and *ppos are handled]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/s390/mm')
-rw-r--r-- | arch/s390/mm/cmm.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/s390/mm/cmm.c b/arch/s390/mm/cmm.c index 79ddd580d605..ca6fab51eea1 100644 --- a/arch/s390/mm/cmm.c +++ b/arch/s390/mm/cmm.c @@ -306,16 +306,16 @@ static int cmm_timeout_handler(struct ctl_table *ctl, int write, } 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); @@ -323,9 +323,9 @@ static int cmm_timeout_handler(struct ctl_table *ctl, int write, len = *lenp; if (copy_to_user(buffer, buf, len)) return -EFAULT; + *lenp = len; + *ppos += len; } - *lenp = len; - *ppos += len; return 0; } |