rds: fix an integer overflow test in rds_info_getsockopt()

"len" is a signed integer.  We check that len is not negative, so it
goes from zero to INT_MAX.  PAGE_SIZE is unsigned long so the comparison
is type promoted to unsigned long.  ULONG_MAX - 4095 is a higher than
INT_MAX so the condition can never be true.

I don't know if this is harmful but it seems safe to limit "len" to
INT_MAX - 4095.

Fixes: a8c879a7ee ('RDS: Info and stats')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Dan Carpenter 2015-08-01 15:33:26 +03:00 коммит произвёл David S. Miller
Родитель 636dba8e12
Коммит 468b732b6f
1 изменённых файлов: 1 добавлений и 1 удалений

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@ -176,7 +176,7 @@ int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval,
/* check for all kinds of wrapping and the like */
start = (unsigned long)optval;
if (len < 0 || len + PAGE_SIZE - 1 < len || start + len < start) {
if (len < 0 || len > INT_MAX - PAGE_SIZE + 1 || start + len < start) {
ret = -EINVAL;
goto out;
}