Commit f6f66c1b authored Apr 10, 2018 by Kees Cook Committed by Linus Torvalds Apr 11, 2018

lib/test_bitmap.c: do not accidentally use stack VLA

This avoids an accidental stack VLA (since the compiler thinks the value
of "len" can change, even when marked "const").  This just replaces it
with a #define so it will DTRT.

Seen with -Wvla.  Fixed as part of the directive to remove all VLAs from
the kernel: https://lkml.org/lkml/2018/3/7/621

Link: http://lkml.kernel.org/r/20180307212555.GA17927@beast


Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Yury Norov <ynorov@caviumnetworks.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 5f00ae0d

lib/test_bitmap.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -296,15 +296,17 @@ static void __init test_bitmap_parselist(void)
		}
		}

		#define EXP_BYTES (sizeof(exp) * 8)

		static void __init test_bitmap_arr32(void)
		{
		unsigned int nbits, next_bit, len = sizeof(exp) * 8;
		unsigned int nbits, next_bit;
		u32 arr[sizeof(exp) / 4];
		DECLARE_BITMAP(bmap2, len);
		DECLARE_BITMAP(bmap2, EXP_BYTES);

		memset(arr, 0xa5, sizeof(arr));

		for (nbits = 0; nbits < len; ++nbits) {
		for (nbits = 0; nbits < EXP_BYTES; ++nbits) {
		bitmap_to_arr32(arr, exp, nbits);
		bitmap_from_arr32(bmap2, arr, nbits);
		expect_eq_bitmap(bmap2, exp, nbits);
		@@ -316,7 +318,7 @@ static void __init test_bitmap_arr32(void)
		" tail is not safely cleared: %d\n",
		nbits, next_bit);

		if (nbits < len - 32)
		if (nbits < EXP_BYTES - 32)
		expect_eq_uint(arr[DIV_ROUND_UP(nbits, 32)],
		0xa5a5a5a5);
		}

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