From: Andrew Morton <akpm@linux-foundation.org>
To: mm-commits@vger.kernel.org,dmantipov@yandex.ru,andriy.shevchenko@intel.com,adobriyan@gmail.com,akpm@linux-foundation.org
Subject: [failures] revert-lib-fix-_parse_integer_limit-to-handle-overflow.patch removed from -mm tree
Date: Sat, 04 Jul 2026 20:25:19 -0700 [thread overview]
Message-ID: <20260705032519.EEEB51F000E9@smtp.kernel.org> (raw)
The quilt patch titled
Subject: Revert "lib: fix _parse_integer_limit() to handle overflow"
has been removed from the -mm tree. Its filename was
revert-lib-fix-_parse_integer_limit-to-handle-overflow.patch
This patch was dropped because it had testing failures
------------------------------------------------------
From: Alexey Dobriyan <adobriyan@gmail.com>
Subject: Revert "lib: fix _parse_integer_limit() to handle overflow"
Date: Thu, 2 Jul 2026 21:06:38 +0300
This reverts commit 6e30111dbb40 ("lib: fix _parse_integer_limit() to
handle overflow").
1) this patch breaks scanf() which uses _parse_integer_limit()
internally, and is supposed to get overflowed result
(however incorrect it may be)
2) using check_mul_overflow() and check_add_overflow() as written
doesn't add any overflow protection because it is under branch
where such overflow can't happen if radix is kept <=16,
3) kernel-doc comment legitimize the function while exactly
the opposite should be done. Not a fan.
Link: https://lore.kernel.org/20260702180638.39196-1-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andriy Shevchenko <andriy.shevchenko@intel.com>
Cc: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
lib/kstrtox.c | 37 +++++++++++++++----------------------
1 file changed, 15 insertions(+), 22 deletions(-)
--- a/lib/kstrtox.c~revert-lib-fix-_parse_integer_limit-to-handle-overflow
+++ a/lib/kstrtox.c
@@ -39,30 +39,25 @@ const char *_parse_integer_fixup_radix(c
return s;
}
-/**
- * _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. A maximum of max_chars characters will be converted.
*
- * 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.
- *
- * Return: Number of characters consumed, maybe ORed with overflow bit
+ * Don't you dare use this function.
*/
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;
- for (rv = 0; rv < max_chars; rv++, s++) {
+ rv = 0;
+ while (max_chars--) {
unsigned int c = *s;
unsigned int lc = _tolower(c);
unsigned int val;
@@ -81,17 +76,15 @@ unsigned int _parse_integer_limit(const
* it in the max base we support (16)
*/
if (unlikely(res & (~0ull << 60))) {
- if (check_mul_overflow(res, base, &res) ||
- check_add_overflow(res, val, &res)) {
- res = ULLONG_MAX;
- overflow = KSTRTOX_OVERFLOW;
- }
- } else {
- res = res * base + val;
+ if (res > div_u64(ULLONG_MAX - val, base))
+ rv |= KSTRTOX_OVERFLOW;
}
+ res = res * base + val;
+ rv++;
+ s++;
}
*p = res;
- return rv | overflow;
+ return rv;
}
noinline
_
Patches currently in -mm which might be from adobriyan@gmail.com are
reply other threads:[~2026-07-05 3:25 UTC|newest]
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