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Kees CookandRafael J. Wysocki 97f7d3f9c9 ACPICA: Replace strncpy() with strscpy_pad() in acpi_ut_safe_strncpy()
Replace the deprecated[1] strncpy() with strscpy_pad() in
acpi_ut_safe_strncpy().

The function is a "safe strncpy" wrapper that does
strncpy(dest, source, dest_size) followed by manual NUL-termination
at dest[dest_size - 1]. strscpy_pad() is a direct replacement: it
NUL-terminates, zero-pads the remainder, and the manual termination
is no longer needed.

All callers pass NUL-terminated source strings (C string literals,
__FILE__ via ACPI_MODULE_NAME, or user-provided filenames that have
already been validated). The destinations are fixed-size char arrays
in ACPICA internal structures (allocation->module, aml_op_name,
acpi_gbl_db_debug_filename), all consumed as C strings.

No behavioral change: strscpy_pad() produces identical output to
strncpy() + manual NUL-termination for NUL-terminated sources that
are shorter than dest_size. For sources longer than dest_size,
strncpy() wrote dest_size non-NUL bytes then the manual termination
overwrote the last byte with NUL; strscpy_pad() writes dest_size-1
bytes plus NUL: same result.

Link: https://github.com/KSPP/linux/issues/90 [1]
Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20260323172451.work.079-kees@kernel.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2026-03-23 18:32:34 +01:00

175 lines
4.3 KiB
C

// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/*******************************************************************************
*
* Module Name: utnonansi - Non-ansi C library functions
*
******************************************************************************/
#include <acpi/acpi.h>
#include "accommon.h"
#define _COMPONENT ACPI_UTILITIES
ACPI_MODULE_NAME("utnonansi")
/*
* Non-ANSI C library functions - strlwr, strupr, stricmp, and "safe"
* string functions.
*/
/*******************************************************************************
*
* FUNCTION: acpi_ut_strlwr (strlwr)
*
* PARAMETERS: src_string - The source string to convert
*
* RETURN: None
*
* DESCRIPTION: Convert a string to lowercase
*
******************************************************************************/
void acpi_ut_strlwr(char *src_string)
{
char *string;
ACPI_FUNCTION_ENTRY();
if (!src_string) {
return;
}
/* Walk entire string, lowercasing the letters */
for (string = src_string; *string; string++) {
*string = (char)tolower((int)*string);
}
}
/*******************************************************************************
*
* FUNCTION: acpi_ut_strupr (strupr)
*
* PARAMETERS: src_string - The source string to convert
*
* RETURN: None
*
* DESCRIPTION: Convert a string to uppercase
*
******************************************************************************/
void acpi_ut_strupr(char *src_string)
{
char *string;
ACPI_FUNCTION_ENTRY();
if (!src_string) {
return;
}
/* Walk entire string, uppercasing the letters */
for (string = src_string; *string; string++) {
*string = (char)toupper((int)*string);
}
}
/******************************************************************************
*
* FUNCTION: acpi_ut_stricmp (stricmp)
*
* PARAMETERS: string1 - first string to compare
* string2 - second string to compare
*
* RETURN: int that signifies string relationship. Zero means strings
* are equal.
*
* DESCRIPTION: Case-insensitive string compare. Implementation of the
* non-ANSI stricmp function.
*
******************************************************************************/
int acpi_ut_stricmp(char *string1, char *string2)
{
int c1;
int c2;
do {
c1 = tolower((int)*string1);
c2 = tolower((int)*string2);
string1++;
string2++;
}
while ((c1 == c2) && (c1));
return (c1 - c2);
}
#if defined (ACPI_DEBUGGER) || defined (ACPI_APPLICATION) || defined (ACPI_DEBUG_OUTPUT)
/*******************************************************************************
*
* FUNCTION: acpi_ut_safe_strcpy, acpi_ut_safe_strcat, acpi_ut_safe_strncat
*
* PARAMETERS: Adds a "DestSize" parameter to each of the standard string
* functions. This is the size of the Destination buffer.
*
* RETURN: TRUE if the operation would overflow the destination buffer.
*
* DESCRIPTION: Safe versions of standard Clib string functions. Ensure that
* the result of the operation will not overflow the output string
* buffer.
*
* NOTE: These functions are typically only helpful for processing
* user input and command lines. For most ACPICA code, the
* required buffer length is precisely calculated before buffer
* allocation, so the use of these functions is unnecessary.
*
******************************************************************************/
u8 acpi_ut_safe_strcpy(char *dest, acpi_size dest_size, char *source)
{
if (strlen(source) >= dest_size) {
return (TRUE);
}
strcpy(dest, source);
return (FALSE);
}
u8 acpi_ut_safe_strcat(char *dest, acpi_size dest_size, char *source)
{
if ((strlen(dest) + strlen(source)) >= dest_size) {
return (TRUE);
}
strcat(dest, source);
return (FALSE);
}
u8
acpi_ut_safe_strncat(char *dest,
acpi_size dest_size,
char *source, acpi_size max_transfer_length)
{
acpi_size actual_transfer_length;
actual_transfer_length = ACPI_MIN(max_transfer_length, strlen(source));
if ((strlen(dest) + actual_transfer_length) >= dest_size) {
return (TRUE);
}
strncat(dest, source, max_transfer_length);
return (FALSE);
}
void acpi_ut_safe_strncpy(char *dest, char *source, acpi_size dest_size)
{
/* Always terminate destination string */
strscpy_pad(dest, source, dest_size);
}
#endif