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| author | Yihui ZENG <yzeng56@asu.edu> | 2019-10-25 12:31:48 +0300 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2019-10-31 17:26:48 +0100 |
| commit | b8e51a6a9db94bc1fb18ae831b3dab106b5a4b5f (patch) | |
| tree | 84dd3a01c06ab6464064d591b3d03003da9e49e6 /arch/s390 | |
| parent | d6d5df1db6e9d7f8f76d2911707f7d5877251b02 (diff) | |
| download | linux-b8e51a6a9db94bc1fb18ae831b3dab106b5a4b5f.tar.bz2 | |
s390/cmm: fix information leak in cmm_timeout_handler()
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>
Diffstat (limited to 'arch/s390')
| -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 510a18299196..a51c892f14f3 100644 --- a/arch/s390/mm/cmm.c +++ b/arch/s390/mm/cmm.c @@ -298,16 +298,16 @@ 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); @@ -315,9 +315,9 @@ 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; } |