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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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91d150c0cc
We currently parse the command non-destructively, to avoid having to allocate memory for a copy before passing it to the standard parsing routines that are used by the core kernel, and which modify the input to delineate the parsed tokens with NUL characters. Instead, we call strstr() and strncmp() to go over the input multiple times, and match prefixes rather than tokens, which implies that we would match, e.g., 'nokaslrfoo' in the stub and disable KASLR, while the kernel would disregard the option and run with KASLR enabled. In order to avoid having to reason about whether and how this behavior may be abused, let's clean up the parsing routines, and rebuild them on top of the existing helpers. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
115 lines
2.1 KiB
C
115 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Taken from:
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* linux/lib/string.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/ctype.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#ifndef __HAVE_ARCH_STRSTR
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/**
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* strstr - Find the first substring in a %NUL terminated string
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* @s1: The string to be searched
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* @s2: The string to search for
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*/
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char *strstr(const char *s1, const char *s2)
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{
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size_t l1, l2;
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l2 = strlen(s2);
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if (!l2)
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return (char *)s1;
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l1 = strlen(s1);
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while (l1 >= l2) {
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l1--;
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if (!memcmp(s1, s2, l2))
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return (char *)s1;
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s1++;
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}
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return NULL;
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}
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#endif
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#ifndef __HAVE_ARCH_STRNCMP
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/**
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* strncmp - Compare two length-limited strings
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* @cs: One string
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* @ct: Another string
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* @count: The maximum number of bytes to compare
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*/
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int strncmp(const char *cs, const char *ct, size_t count)
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{
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unsigned char c1, c2;
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while (count) {
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c1 = *cs++;
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c2 = *ct++;
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if (c1 != c2)
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return c1 < c2 ? -1 : 1;
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if (!c1)
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break;
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count--;
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}
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return 0;
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}
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#endif
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/* Works only for digits and letters, but small and fast */
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#define TOLOWER(x) ((x) | 0x20)
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static unsigned int simple_guess_base(const char *cp)
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{
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if (cp[0] == '0') {
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if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
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return 16;
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else
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return 8;
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} else {
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return 10;
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}
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}
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/**
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* simple_strtoull - convert a string to an unsigned long long
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* @cp: The start of the string
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* @endp: A pointer to the end of the parsed string will be placed here
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* @base: The number base to use
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*/
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unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
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{
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unsigned long long result = 0;
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if (!base)
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base = simple_guess_base(cp);
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if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
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cp += 2;
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while (isxdigit(*cp)) {
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unsigned int value;
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value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
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if (value >= base)
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break;
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result = result * base + value;
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cp++;
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}
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if (endp)
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*endp = (char *)cp;
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return result;
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}
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long simple_strtol(const char *cp, char **endp, unsigned int base)
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{
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if (*cp == '-')
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return -simple_strtoull(cp + 1, endp, base);
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return simple_strtoull(cp, endp, base);
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}
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