From: Dmitry Antipov <dmantipov@yandex.ru>
Date: Tue, 19 May 2026 17:22:53 +0000 (+0300)
Subject: lib: fix memparse() to handle overflow
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9a4580db6e9f83428813f671a79486469684069f;p=thirdparty%2Flinux.git

lib: fix memparse() to handle overflow

Since '_parse_integer_limit()' (and so 'simple_strtoull()') is now capable
to handle overflow, adjust 'memparse()' to handle overflow (denoted by
ULLONG_MAX) returned from 'simple_strtoull()'.  Also use
'check_shl_overflow()' to catch an overflow possibly caused by processing
size suffix and denote it with ULLONG_MAX as well.

Link: https://lore.kernel.org/20260519172259.908980-3-dmantipov@yandex.ru
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Charlie Jenkins <thecharlesjenkins@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/lib/cmdline.c b/lib/cmdline.c
index 90ed997d9570..f6e4b113ca9f 100644
--- a/lib/cmdline.c
+++ b/lib/cmdline.c
@@ -150,39 +150,46 @@ EXPORT_SYMBOL(get_options);
 unsigned long long memparse(const char *ptr, char **retptr)
 {
 	char *endptr;	/* local pointer to end of parsed string */
-
 	unsigned long long ret = simple_strtoull(ptr, &endptr, 0);
+	unsigned int shl = 0;
 
+	/* Consume valid suffix even in case of overflow. */
 	switch (*endptr) {
 	case 'E':
 	case 'e':
-		ret <<= 10;
+		shl += 10;
 		fallthrough;
 	case 'P':
 	case 'p':
-		ret <<= 10;
+		shl += 10;
 		fallthrough;
 	case 'T':
 	case 't':
-		ret <<= 10;
+		shl += 10;
 		fallthrough;
 	case 'G':
 	case 'g':
-		ret <<= 10;
+		shl += 10;
 		fallthrough;
 	case 'M':
 	case 'm':
-		ret <<= 10;
+		shl += 10;
 		fallthrough;
 	case 'K':
 	case 'k':
-		ret <<= 10;
-		endptr++;
+		shl += 10;
 		fallthrough;
 	default:
 		break;
 	}
 
+	if (shl && likely(ptr != endptr)) {
+		/* Have valid suffix with preceding number. */
+		if (unlikely(check_shl_overflow(ret, shl, &ret)))
+			ret = ULLONG_MAX;
+		endptr++;
+	}
+
 	if (retptr)
 		*retptr = endptr;