"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: a8c879a7ee98 ('RDS: Info and stats')
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
diff --git a/net/rds/info.c b/net/rds/info.c
index 9a6b4f6..140a44a 100644
--- a/net/rds/info.c
+++ b/net/rds/info.c
@@ -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;
}
--
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