Files
linux/lib
Kees Cook 5e88c48cb4 kbuild: Switch from -Wvla to -Wvla-larger-than=1
Variable Length Arrays (VLAs) on the stack must not be used in the kernel.
Function parameter VLAs[1] should be usable, but -Wvla will warn for
those. For example, this will produce a warning but it is not using a
stack VLA:

    int something(size_t n, int array[n]) { ...

Clang has no way yet to distinguish between the VLA types[2], so
depend on GCC for now to keep stack VLAs out of the tree by using GCC's
-Wvla-larger-than=N option (though GCC may split -Wvla similarly[3] to
how Clang is planning to).

While GCC 8+ supports -Wvla-larger-than, only 9+ supports ...=0[4],
so use -Wvla-larger-than=1. Adjust mm/kasan/Makefile to remove it from
CFLAGS (GCC <9 appears unable to disable the warning correctly[5]).

The VLA usage in lib/test_ubsan.c was removed in commit 9d7ca61b13
("lib/test_ubsan.c: VLA no longer used in kernel") so the lib/Makefile
disabling of VLA checking can be entirely removed.

Link: https://en.cppreference.com/w/c/language/array [1]
Link: https://github.com/llvm/llvm-project/issues/57098 [2]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98217 [3]
Link: https://lore.kernel.org/lkml/7780883c-0ac8-4aaa-b850-469e33b50672@linux.ibm.com/ [4]
Link: https://lore.kernel.org/r/202505071331.4iOzqmuE-lkp@intel.com/ [5]
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Link: https://lore.kernel.org/r/20250418213235.work.532-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2025-05-08 09:42:06 -07:00
..
2024-12-12 18:26:32 +01:00
2025-03-16 22:30:49 -07:00
2025-04-11 17:32:38 -07:00
2025-04-11 17:32:37 -07:00
2024-07-12 16:39:53 -07:00
2024-02-01 13:06:40 +01:00
2021-08-19 09:02:55 +09:00
2023-02-02 22:50:01 -08:00
2023-02-02 22:50:01 -08:00
2021-01-03 20:05:18 -05:00
2025-03-25 10:18:31 -03:00
2025-01-12 20:21:15 -08:00
2021-08-19 09:02:55 +09:00
2025-04-04 11:31:42 -07:00
2025-01-14 19:45:35 +01:00
2023-08-21 13:46:25 -07:00
2023-10-16 12:44:06 -04:00
2024-10-14 16:33:24 -05:00
2023-10-16 12:44:06 -04:00
2022-10-03 17:34:32 -07:00
2025-03-17 12:17:00 -07:00
2024-07-04 23:43:10 -07:00
2021-07-08 11:48:20 -07:00
2024-02-15 12:17:28 -05:00
2021-06-18 11:43:09 +02:00
2025-03-25 10:18:31 -03:00
2024-06-10 11:14:52 +01:00
2024-12-09 13:48:29 -08:00