From dd5e024956bf3035be380a3f022b77c06166112a Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 6 Aug 2020 15:57:28 +0100 Subject: [PATCH] drm/i915/selftests: Prevent selecting 0 for our random width/align When igt_random_offset() is a given a range of [0, PAGE_SIZE], it is allowed to return 0. However, attempting to use a size of 0 for the igt_lmem_write_cpu() byte poking, leads to call igt_random_offset() with a range of [offset, offset + 0] and ask it to find a length of 4 within it. This triggers the bug on that the requested length should fit within the range! Signed-off-by: Chris Wilson Cc: Matthew Auld Reviewed-by: Matthew Auld Link: https://patchwork.freedesktop.org/patch/msgid/20200806145728.16495-1-chris@chris-wilson.co.uk Signed-off-by: Rodrigo Vivi Signed-off-by: Joonas Lahtinen --- drivers/gpu/drm/i915/selftests/intel_memory_region.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c index 6e80d99048e4..741270fcb6b9 100644 --- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c +++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c @@ -522,9 +522,9 @@ static int igt_lmem_write_cpu(void *arg) goto out_unpin; } - /* We want to throw in a random width/align */ - bytes[0] = igt_random_offset(&prng, 0, PAGE_SIZE, sizeof(u32), - sizeof(u32)); + /* A random multiple of u32, picked between [64, PAGE_SIZE - 64] */ + bytes[0] = igt_random_offset(&prng, 64, PAGE_SIZE - 64, 0, sizeof(u32)); + GEM_BUG_ON(!IS_ALIGNED(bytes[0], sizeof(u32))); i = 0; do { -- 2.39.5