Merge tag 'overflow-v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull overflow updates from Kees Cook:
 "The end goal of the current buffer overflow detection work[0] is to
  gain full compile-time and run-time coverage of all detectable buffer
  overflows seen via array indexing or memcpy(), memmove(), and
  memset(). The str*() family of functions already have full coverage.

  While much of the work for these changes have been on-going for many
  releases (i.e. 0-element and 1-element array replacements, as well as
  avoiding false positives and fixing discovered overflows[1]), this
  series contains the foundational elements of several related buffer
  overflow detection improvements by providing new common helpers and
  FORTIFY_SOURCE changes needed to gain the introspection required for
  compiler visibility into array sizes. Also included are a handful of
  already Acked instances using the helpers (or related clean-ups), with
  many more waiting at the ready to be taken via subsystem-specific
  trees[2].

  The new helpers are:

   - struct_group() for gaining struct member range introspection

   - memset_after() and memset_startat() for clearing to the end of
     structures

   - DECLARE_FLEX_ARRAY() for using flex arrays in unions or alone in
     structs

  Also included is the beginning of the refactoring of FORTIFY_SOURCE to
  support memcpy() introspection, fix missing and regressed coverage
  under GCC, and to prepare to fix the currently broken Clang support.
  Finishing this work is part of the larger series[0], but depends on
  all the false positives and buffer overflow bug fixes to have landed
  already and those that depend on this series to land.

  As part of the FORTIFY_SOURCE refactoring, a set of both a
  compile-time and run-time tests are added for FORTIFY_SOURCE and the
  mem*()-family functions respectively. The compile time tests have
  found a legitimate (though corner-case) bug[6] already.

  Please note that the appearance of "panic" and "BUG" in the
  FORTIFY_SOURCE refactoring are the result of relocating existing code,
  and no new use of those code-paths are expected nor desired.

  Finally, there are two tree-wide conversions for 0-element arrays and
  flexible array unions to gain sane compiler introspection coverage
  that result in no known object code differences.

  After this series (and the changes that have now landed via netdev and
  usb), we are very close to finally being able to build with
  -Warray-bounds and -Wzero-length-bounds.

  However, due corner cases in GCC[3] and Clang[4], I have not included
  the last two patches that turn on these options, as I don't want to
  introduce any known warnings to the build. Hopefully these can be
  solved soon"

Link: https://lore.kernel.org/lkml/20210818060533.3569517-1-keescook@chromium.org/ [0]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?qt=grep&q=FORTIFY_SOURCE [1]
Link: https://lore.kernel.org/lkml/202108220107.3E26FE6C9C@keescook/ [2]
Link: https://lore.kernel.org/lkml/3ab153ec-2798-da4c-f7b1-81b0ac8b0c5b@roeck-us.net/ [3]
Link: https://bugs.llvm.org/show_bug.cgi?id=51682 [4]
Link: https://lore.kernel.org/lkml/202109051257.29B29745C0@keescook/ [5]
Link: https://lore.kernel.org/lkml/20211020200039.170424-1-keescook@chromium.org/ [6]

* tag 'overflow-v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (30 commits)
  fortify: strlen: Avoid shadowing previous locals
  compiler-gcc.h: Define __SANITIZE_ADDRESS__ under hwaddress sanitizer
  treewide: Replace 0-element memcpy() destinations with flexible arrays
  treewide: Replace open-coded flex arrays in unions
  stddef: Introduce DECLARE_FLEX_ARRAY() helper
  btrfs: Use memset_startat() to clear end of struct
  string.h: Introduce memset_startat() for wiping trailing members and padding
  xfrm: Use memset_after() to clear padding
  string.h: Introduce memset_after() for wiping trailing members/padding
  lib: Introduce CONFIG_MEMCPY_KUNIT_TEST
  fortify: Add compile-time FORTIFY_SOURCE tests
  fortify: Allow strlen() and strnlen() to pass compile-time known lengths
  fortify: Prepare to improve strnlen() and strlen() warnings
  fortify: Fix dropped strcpy() compile-time write overflow check
  fortify: Explicitly disable Clang support
  fortify: Move remaining fortify helpers into fortify-string.h
  lib/string: Move helper functions out of string.c
  compiler_types.h: Remove __compiletime_object_size()
  cm4000_cs: Use struct_group() to zero struct cm4000_dev region
  can: flexcan: Use struct_group() to zero struct flexcan_regs regions
  ...

1 files changed, 6 insertions, 204 deletions

diff --git a/lib/string.c b/lib/string.c
index b2de45a581f4..485777c9da83 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -6,20 +6,15 @@
  */
 
 /*
- * stupid library routines.. The optimized versions should generally be found
- * as inline code in <asm-xx/string.h>
+ * This file should be used only for "library" routines that may have
+ * alternative implementations on specific architectures (generally
+ * found in <asm-xx/string.h>), or get overloaded by FORTIFY_SOURCE.
+ * (Specifically, this file is built with __NO_FORTIFY.)
  *
- * These are buggy as well..
- *
- * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
- * -  Added strsep() which will replace strtok() soon (because strsep() is
- *    reentrant and should be faster). Use only strsep() in new code, please.
- *
- * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
- *                    Matthew Hawkins <matt@mh.dropbear.id.au>
- * -  Kissed strtok() goodbye
+ * Other helper functions should live in string_helpers.c.
  */
 
+#define __NO_FORTIFY
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/ctype.h>
@@ -239,40 +234,6 @@ EXPORT_SYMBOL(strscpy);
 #endif
 
 /**
- * strscpy_pad() - Copy a C-string into a sized buffer
- * @dest: Where to copy the string to
- * @src: Where to copy the string from
- * @count: Size of destination buffer
- *
- * Copy the string, or as much of it as fits, into the dest buffer.  The
- * behavior is undefined if the string buffers overlap.  The destination
- * buffer is always %NUL terminated, unless it's zero-sized.
- *
- * If the source string is shorter than the destination buffer, zeros
- * the tail of the destination buffer.
- *
- * For full explanation of why you may want to consider using the
- * 'strscpy' functions please see the function docstring for strscpy().
- *
- * Returns:
- * * The number of characters copied (not including the trailing %NUL)
- * * -E2BIG if count is 0 or @src was truncated.
- */
-ssize_t strscpy_pad(char *dest, const char *src, size_t count)
-{
-	ssize_t written;
-
-	written = strscpy(dest, src, count);
-	if (written < 0 || written == count - 1)
-		return written;
-
-	memset(dest + written + 1, 0, count - written - 1);
-
-	return written;
-}
-EXPORT_SYMBOL(strscpy_pad);
-
-/**
  * stpcpy - copy a string from src to dest returning a pointer to the new end
  *          of dest, including src's %NUL-terminator. May overrun dest.
  * @dest: pointer to end of string being copied into. Must be large enough
@@ -514,46 +475,6 @@ char *strnchr(const char *s, size_t count, int c)
 EXPORT_SYMBOL(strnchr);
 #endif
 
-/**
- * skip_spaces - Removes leading whitespace from @str.
- * @str: The string to be stripped.
- *
- * Returns a pointer to the first non-whitespace character in @str.
- */
-char *skip_spaces(const char *str)
-{
-	while (isspace(*str))
-		++str;
-	return (char *)str;
-}
-EXPORT_SYMBOL(skip_spaces);
-
-/**
- * strim - Removes leading and trailing whitespace from @s.
- * @s: The string to be stripped.
- *
- * Note that the first trailing whitespace is replaced with a %NUL-terminator
- * in the given string @s. Returns a pointer to the first non-whitespace
- * character in @s.
- */
-char *strim(char *s)
-{
-	size_t size;
-	char *end;
-
-	size = strlen(s);
-	if (!size)
-		return s;
-
-	end = s + size - 1;
-	while (end >= s && isspace(*end))
-		end--;
-	*(end + 1) = '\0';
-
-	return skip_spaces(s);
-}
-EXPORT_SYMBOL(strim);
-
 #ifndef __HAVE_ARCH_STRLEN
 /**
  * strlen - Find the length of a string
@@ -688,101 +609,6 @@ char *strsep(char **s, const char *ct)
 EXPORT_SYMBOL(strsep);
 #endif
 
-/**
- * sysfs_streq - return true if strings are equal, modulo trailing newline
- * @s1: one string
- * @s2: another string
- *
- * This routine returns true iff two strings are equal, treating both
- * NUL and newline-then-NUL as equivalent string terminations.  It's
- * geared for use with sysfs input strings, which generally terminate
- * with newlines but are compared against values without newlines.
- */
-bool sysfs_streq(const char *s1, const char *s2)
-{
-	while (*s1 && *s1 == *s2) {
-		s1++;
-		s2++;
-	}
-
-	if (*s1 == *s2)
-		return true;
-	if (!*s1 && *s2 == '\n' && !s2[1])
-		return true;
-	if (*s1 == '\n' && !s1[1] && !*s2)
-		return true;
-	return false;
-}
-EXPORT_SYMBOL(sysfs_streq);
-
-/**
- * match_string - matches given string in an array
- * @array:	array of strings
- * @n:		number of strings in the array or -1 for NULL terminated arrays
- * @string:	string to match with
- *
- * This routine will look for a string in an array of strings up to the
- * n-th element in the array or until the first NULL element.
- *
- * Historically the value of -1 for @n, was used to search in arrays that
- * are NULL terminated. However, the function does not make a distinction
- * when finishing the search: either @n elements have been compared OR
- * the first NULL element was found.
- *
- * Return:
- * index of a @string in the @array if matches, or %-EINVAL otherwise.
- */
-int match_string(const char * const *array, size_t n, const char *string)
-{
-	int index;
-	const char *item;
-
-	for (index = 0; index < n; index++) {
-		item = array[index];
-		if (!item)
-			break;
-		if (!strcmp(item, string))
-			return index;
-	}
-
-	return -EINVAL;
-}
-EXPORT_SYMBOL(match_string);
-
-/**
- * __sysfs_match_string - matches given string in an array
- * @array: array of strings
- * @n: number of strings in the array or -1 for NULL terminated arrays
- * @str: string to match with
- *
- * Returns index of @str in the @array or -EINVAL, just like match_string().
- * Uses sysfs_streq instead of strcmp for matching.
- *
- * This routine will look for a string in an array of strings up to the
- * n-th element in the array or until the first NULL element.
- *
- * Historically the value of -1 for @n, was used to search in arrays that
- * are NULL terminated. However, the function does not make a distinction
- * when finishing the search: either @n elements have been compared OR
- * the first NULL element was found.
- */
-int __sysfs_match_string(const char * const *array, size_t n, const char *str)
-{
-	const char *item;
-	int index;
-
-	for (index = 0; index < n; index++) {
-		item = array[index];
-		if (!item)
-			break;
-		if (sysfs_streq(item, str))
-			return index;
-	}
-
-	return -EINVAL;
-}
-EXPORT_SYMBOL(__sysfs_match_string);
-
 #ifndef __HAVE_ARCH_MEMSET
 /**
  * memset - Fill a region of memory with the given value
@@ -1141,27 +967,3 @@ void *memchr_inv(const void *start, int c, size_t bytes)
 	return check_bytes8(start, value, bytes % 8);
 }
 EXPORT_SYMBOL(memchr_inv);
-
-/**
- * strreplace - Replace all occurrences of character in string.
- * @s: The string to operate on.
- * @old: The character being replaced.
- * @new: The character @old is replaced with.
- *
- * Returns pointer to the nul byte at the end of @s.
- */
-char *strreplace(char *s, char old, char new)
-{
-	for (; *s; ++s)
-		if (*s == old)
-			*s = new;
-	return s;
-}
-EXPORT_SYMBOL(strreplace);
-
-void fortify_panic(const char *name)
-{
-	pr_emerg("detected buffer overflow in %s\n", name);
-	BUG();
-}
-EXPORT_SYMBOL(fortify_panic);