From: Kees Cook <keescook@xxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/test_bitmap.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff -puN lib/test_bitmap.c~test_bitmap-do-not-accidentally-use-stack-vla lib/test_bitmap.c --- a/lib/test_bitmap.c~test_bitmap-do-not-accidentally-use-stack-vla +++ a/lib/test_bitmap.c @@ -296,15 +296,17 @@ static void __init test_bitmap_parselist } } +#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(voi " 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); } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
