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, 4 insertions, 5 deletions

diff --git a/drivers/char/pcmcia/cm4000_cs.c b/drivers/char/pcmcia/cm4000_cs.c
index 8f1bce0b4fe5..adaec8fd4b16 100644
--- a/drivers/char/pcmcia/cm4000_cs.c
+++ b/drivers/char/pcmcia/cm4000_cs.c
@@ -116,8 +116,9 @@ struct cm4000_dev {
 	wait_queue_head_t atrq;		/* wait for ATR valid */
 	wait_queue_head_t readq;	/* used by write to wake blk.read */
 
-	/* warning: do not move this fields.
+	/* warning: do not move this struct group.
 	 * initialising to zero depends on it - see ZERO_DEV below.  */
+	struct_group(init,
 	unsigned char atr_csum;
 	unsigned char atr_len_retry;
 	unsigned short atr_len;
@@ -140,12 +141,10 @@ struct cm4000_dev {
 
 	struct timer_list timer;	/* used to keep monitor running */
 	int monitor_running;
+	);
 };
 
-#define	ZERO_DEV(dev)  						\
-	memset(&dev->atr_csum,0,				\
-		sizeof(struct cm4000_dev) - 			\
-		offsetof(struct cm4000_dev, atr_csum))
+#define	ZERO_DEV(dev)	memset(&((dev)->init), 0, sizeof((dev)->init))
 
 static struct pcmcia_device *dev_table[CM4000_MAX_DEV];
 static struct class *cmm_class;