Ping. On 04/16/2015 03:52 PM, Brian Paul wrote:
This should be more efficient than the previous snprintf() solution. But more importantly, it avoids a buffer overflow bug that could result in crashes or unpredictable results when processing very large interface blocks.For the app in question, key->length = 103 for some interfaces. The check if size >= sizeof(hash_key) was insufficient to prevent overflows of the hash_key[128] array because it didn't account for the terminating zero. In this case, this caused the call to hash_table_string_hash() to return different results for identical inputs, and then shader linking failed. This new solution also takes all structure fields into account instead of just the first 15 when sizeof(pointer)==8. Cc: mesa-sta...@lists.freedesktop.org --- src/glsl/glsl_types.cpp | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) diff --git a/src/glsl/glsl_types.cpp b/src/glsl/glsl_types.cpp index 4aa36a7..9c9b7ef 100644 --- a/src/glsl/glsl_types.cpp +++ b/src/glsl/glsl_types.cpp @@ -738,24 +738,27 @@ glsl_type::record_key_compare(const void *a, const void *b) } +/** + * Generate an integer hash value for a glsl_type structure type. + */ unsigned glsl_type::record_key_hash(const void *a) { const glsl_type *const key = (glsl_type *) a; - char hash_key[128]; - unsigned size = 0; - - size = snprintf(hash_key, sizeof(hash_key), "%08x", key->length); + uintptr_t hash = key->length; + unsigned retval; for (unsigned i = 0; i < key->length; i++) { - if (size >= sizeof(hash_key)) - break; - - size += snprintf(& hash_key[size], sizeof(hash_key) - size, - "%p", (void *) key->fields.structure[i].type); + /* casting pointer to uintptr_t */ + hash = (hash * 13 ) + (uintptr_t) key->fields.structure[i].type; } - return hash_table_string_hash(& hash_key); + if (sizeof(hash) == 8) + retval = (hash & 0xffffffff) ^ ((uint64_t) hash >> 32); + else + retval = hash; + + return retval; }
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