[PATCH] mm/hugetlb: fix early boot crash on parameters without '=' separator

[Thorsten Blum <thorsten.blum@linux.dev>]

If hugepages, hugepagesz, or default_hugepagesz are specified on the
kernel command line without the '=' separator, early parameter parsing
passes NULL to hugetlb_add_param(), which dereferences it in strlen()
and can crash the system during early boot.

Reject NULL values in hugetlb_add_param() and return -EINVAL instead.

Fixes: 5b47c02967ab ("mm/hugetlb: convert cmdline parameters from setup to early")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 mm/hugetlb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 327eaa4074d3..9fda39132d26 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4252,6 +4252,9 @@ static __init int hugetlb_add_param(char *s, int (*setup)(char *))
 	size_t len;
 	char *p;
 
+	if (!s)
+		return -EINVAL;
+
 	if (hugetlb_param_index >= HUGE_MAX_CMDLINE_ARGS)
 		return -EINVAL;