[PATCH v9 2/6] lib: fix memparse() to handle overflow

Dmitry Antipov
2026-04-03T10:34:06Z

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.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v9: bump version to match the series
v8: do not use temporary in check_shl_overflow()
v7: do not double-adjust endptr and drop
redundant check against ULLONG_MAX
v6: handle valid-suffix-only string like "k"
as unrecognized, minor style adjustments
v5: initial version to join the series
---
lib/cmdline.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)

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;