From c690a7a8cdfb6425547bbb782020098405851194 Mon Sep 17 00:00:00 2001 From: Matt Turner Date: Thu, 23 Nov 2017 10:41:34 -0800 Subject: [PATCH] util: Fix disk_cache index calculation on big endian The cache-test test program attempts to create a collision (using key_a and key_a_collide) by making the first two bytes identical. The idea is fine -- the shader cache wants to use the first four characters of a SHA1 hex digest as the index. The following program unsigned char array[4] = {1, 2, 3, 4}; int *ptr = (int *)array; for (int i = 0; i < 4; i++) { printf("%02x", array[i]); } printf("\n"); printf("%08x\n", *ptr); prints 01020304 04030201 on little endian, and 01020304 01020304 on big endian. On big endian platforms reading the character array back as an int (as is done in disk_cache.c) does not yield the same results as reading the byte array. To get the first four characters of the SHA1 hex digest when we mask with CACHE_INDEX_KEY_MASK, we need to byte swap the int on big endian platforms. Bugzilla: https://bugs.freedesktop.org/103668 Bugzilla: https://bugs.gentoo.org/637060 Bugzilla: https://bugs.gentoo.org/636326 Fixes: 87ab26b2ab35 ("glsl: Add initial functions to implement an on-disk cache") Reviewed-by: Emil Velikov --- src/util/disk_cache.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/util/disk_cache.c b/src/util/disk_cache.c index fde6e2e0974..e95406565e4 100644 --- a/src/util/disk_cache.c +++ b/src/util/disk_cache.c @@ -1170,7 +1170,7 @@ void disk_cache_put_key(struct disk_cache *cache, const cache_key key) { const uint32_t *key_chunk = (const uint32_t *) key; - int i = *key_chunk & CACHE_INDEX_KEY_MASK; + int i = CPU_TO_LE32(*key_chunk) & CACHE_INDEX_KEY_MASK; unsigned char *entry; entry = &cache->stored_keys[i * CACHE_KEY_SIZE]; @@ -1189,7 +1189,7 @@ bool disk_cache_has_key(struct disk_cache *cache, const cache_key key) { const uint32_t *key_chunk = (const uint32_t *) key; - int i = *key_chunk & CACHE_INDEX_KEY_MASK; + int i = CPU_TO_LE32(*key_chunk) & CACHE_INDEX_KEY_MASK; unsigned char *entry; entry = &cache->stored_keys[i * CACHE_KEY_SIZE]; -- 2.30.2