diff options
| author | Dmitry Antipov <dmantipov@yandex.ru> | 2026-05-19 20:22:52 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-05-28 21:24:49 -0700 |
| commit | 6e30111dbb4075e3c26c230417b32bc4a1c66831 (patch) | |
| tree | 730841bb975e71505a3b89e17b3fa2ced60edd1b /lib | |
| parent | dcc8a57815534e3844f342b28ecfb6e626a816a0 (diff) | |
| download | linux-next-history-6e30111dbb4075e3c26c230417b32bc4a1c66831.tar.gz | |
lib: fix _parse_integer_limit() to handle overflow
Patch series "lib and lib/cmdline enhancements", v11.
This series is a merge of the recently posted [1] and [2]. The first one
is intended to adjust '_parse_integer_limit()' and 'memparse()' to not
ignore overflows, extend string to 64-bit integer conversion tests, add
KUnit-based test for 'memparse()' and fix kernel-doc glitches found in
lib/cmdline.c. The second one was originated from RISCV-specific build
fixes needed to integrate the former and now aims to provide
platform-specific double-word shifts and corresponding KUnit test.
Getting feedback from RISCV core maintainers would be very helpful.
Special thanks to Andy Shevchenko, Charlie Jenkins, and Andrew Morton.
This patch (of 8):
In '_parse_integer_limit()', adjust native integer arithmetic with
near-to-overflow branch where 'check_mul_overflow()' and
'check_add_overflow()' are used to check whether an intermediate result
goes out of range, and denote such a case with ULLONG_MAX, thus making the
function more similar to standard C library's 'strtoull()'. Adjust
comment to kernel-doc style as well.
Link: https://lore.kernel.org/20260519172259.908980-1-dmantipov@yandex.ru
Link: https://lore.kernel.org/20260519172259.908980-2-dmantipov@yandex.ru
Link: https://lore.kernel.org/linux-riscv/20260403103338.1122415-1-dmantipov@yandex.ru [1]
Link: https://lore.kernel.org/linux-riscv/20260427090105.705529-1-dmantipov@yandex.ru [2]
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: Andriy Shevchenko <andriy.shevchenko@intel.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Charlie Jenkins <thecharlesjenkins@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/kstrtox.c | 37 |
1 files changed, 22 insertions, 15 deletions
diff --git a/lib/kstrtox.c b/lib/kstrtox.c index 97be2a39f5371..edc4eb7c1bca1 100644 --- a/lib/kstrtox.c +++ b/lib/kstrtox.c @@ -39,25 +39,30 @@ const char *_parse_integer_fixup_radix(const char *s, unsigned int *base) return s; } -/* - * Convert non-negative integer string representation in explicitly given radix - * to an integer. A maximum of max_chars characters will be converted. +/** + * _parse_integer_limit - Convert integer string representation to an integer + * @s: Integer string representation + * @base: Radix + * @p: Where to store result + * @max_chars: Maximum amount of characters to convert + * + * Convert non-negative integer string representation in explicitly given + * radix to an integer. If overflow occurs, value at @p is set to ULLONG_MAX. * - * Return number of characters consumed maybe or-ed with overflow bit. - * If overflow occurs, result integer (incorrect) is still returned. + * This function is the workhorse of other string conversion functions and it + * is discouraged to use it explicitly. Consider kstrto*() family instead. * - * Don't you dare use this function. + * Return: Number of characters consumed, maybe ORed with overflow bit */ noinline unsigned int _parse_integer_limit(const char *s, unsigned int base, unsigned long long *p, size_t max_chars) { + unsigned int rv, overflow = 0; unsigned long long res; - unsigned int rv; res = 0; - rv = 0; - while (max_chars--) { + for (rv = 0; rv < max_chars; rv++, s++) { unsigned int c = *s; unsigned int lc = _tolower(c); unsigned int val; @@ -76,15 +81,17 @@ unsigned int _parse_integer_limit(const char *s, unsigned int base, unsigned lon * it in the max base we support (16) */ if (unlikely(res & (~0ull << 60))) { - if (res > div_u64(ULLONG_MAX - val, base)) - rv |= KSTRTOX_OVERFLOW; + if (check_mul_overflow(res, base, &res) || + check_add_overflow(res, val, &res)) { + res = ULLONG_MAX; + overflow = KSTRTOX_OVERFLOW; + } + } else { + res = res * base + val; } - res = res * base + val; - rv++; - s++; } *p = res; - return rv; + return rv | overflow; } noinline |