* + lib-fix-_parse_integer_limit-to-handle-overflow.patch added to mm-nonmm-unstable branch
@ 2026-04-03 17:10 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2026-04-03 17:10 UTC (permalink / raw)
To: mm-commits, dmantipov, akpm
The patch titled
Subject: lib: fix _parse_integer_limit() to handle overflow
has been added to the -mm mm-nonmm-unstable branch. Its filename is
lib-fix-_parse_integer_limit-to-handle-overflow.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-fix-_parse_integer_limit-to-handle-overflow.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Dmitry Antipov <dmantipov@yandex.ru>
Subject: lib: fix _parse_integer_limit() to handle overflow
Date: Fri, 3 Apr 2026 13:33:33 +0300
Patch series "lib and lib/cmdline enhancements", v9.
Adjust '_parse_integer_limit()' and 'memparse()' to not ignore overflows,
extend string to 64-bit integer conversion tests, add KUnit-based test for
'memparse()', fix kernel-doc glitches found in lib/cmdline.c and adjust
riscv32 linker script to export symbols needed for EFI stub.
This patch (of 6):
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://lkml.kernel.org/r/20260403103338.1122415-1-dmantipov@yandex.ru
Link: https://lkml.kernel.org/r/20260403103338.1122415-2-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: "Darrick J. Wong" <djwong@kernel.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <pjw@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
lib/kstrtox.c | 37 ++++++++++++++++++++++---------------
1 file changed, 22 insertions(+), 15 deletions(-)
--- a/lib/kstrtox.c~lib-fix-_parse_integer_limit-to-handle-overflow
+++ a/lib/kstrtox.c
@@ -39,25 +39,30 @@ const char *_parse_integer_fixup_radix(c
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
*
- * Return number of characters consumed maybe or-ed with overflow bit.
- * If overflow occurs, result integer (incorrect) is still returned.
+ * Convert non-negative integer string representation in explicitly given
+ * radix to an integer. If overflow occurs, value at @p is set to ULLONG_MAX.
*
- * Don't you dare use this function.
+ * 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
*/
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
* 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
_
Patches currently in -mm which might be from dmantipov@yandex.ru are
lib-fix-_parse_integer_limit-to-handle-overflow.patch
lib-fix-memparse-to-handle-overflow.patch
lib-add-more-string-to-64-bit-integer-conversion-overflow-tests.patch
lib-cmdline_kunit-add-test-case-for-memparse.patch
lib-cmdline-adjust-a-few-comments-to-fix-kernel-doc-wreturn-warnings.patch
riscv-export-symbols-needed-for-riscv32-efi-stub.patch
^ permalink raw reply [flat|nested] 2+ messages in thread* + lib-fix-_parse_integer_limit-to-handle-overflow.patch added to mm-nonmm-unstable branch
@ 2026-02-20 21:34 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2026-02-20 21:34 UTC (permalink / raw)
To: mm-commits, kees, djwong, andriy.shevchenko, dmantipov, akpm
The patch titled
Subject: lib: fix _parse_integer_limit() to handle overflow
has been added to the -mm mm-nonmm-unstable branch. Its filename is
lib-fix-_parse_integer_limit-to-handle-overflow.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-fix-_parse_integer_limit-to-handle-overflow.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Dmitry Antipov <dmantipov@yandex.ru>
Subject: lib: fix _parse_integer_limit() to handle overflow
Date: Thu, 12 Feb 2026 19:44:09 +0300
Patch series "lib and lib/cmdline enhancements", v8.
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.
This patch (of 5):
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://lkml.kernel.org/r/20260212164413.889625-1-dmantipov@yandex.ru
Link: https://lkml.kernel.org/r/20260212164413.889625-2-dmantipov@yandex.ru
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
lib/kstrtox.c | 37 ++++++++++++++++++++++---------------
1 file changed, 22 insertions(+), 15 deletions(-)
--- a/lib/kstrtox.c~lib-fix-_parse_integer_limit-to-handle-overflow
+++ a/lib/kstrtox.c
@@ -39,25 +39,30 @@ const char *_parse_integer_fixup_radix(c
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
*
- * Return number of characters consumed maybe or-ed with overflow bit.
- * If overflow occurs, result integer (incorrect) is still returned.
+ * Convert non-negative integer string representation in explicitly given
+ * radix to an integer. If overflow occurs, value at @p is set to ULLONG_MAX.
*
- * Don't you dare use this function.
+ * 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
*/
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
* 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
_
Patches currently in -mm which might be from dmantipov@yandex.ru are
lib-fix-_parse_integer_limit-to-handle-overflow.patch
lib-fix-memparse-to-handle-overflow.patch
lib-add-more-string-to-64-bit-integer-conversion-overflow-tests.patch
lib-cmdline_kunit-add-test-case-for-memparse.patch
lib-cmdline-adjust-a-few-comments-to-fix-kernel-doc-wreturn-warnings.patch
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