glsl: rewrite glsl_type::record_key_hash() to avoid buffer overflow
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-stable@lists.freedesktop.org Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
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@ -738,24 +738,27 @@ glsl_type::record_key_compare(const void *a, const void *b)
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}
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/**
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* Generate an integer hash value for a glsl_type structure type.
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*/
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unsigned
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glsl_type::record_key_hash(const void *a)
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{
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const glsl_type *const key = (glsl_type *) a;
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char hash_key[128];
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unsigned size = 0;
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size = snprintf(hash_key, sizeof(hash_key), "%08x", key->length);
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uintptr_t hash = key->length;
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unsigned retval;
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for (unsigned i = 0; i < key->length; i++) {
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if (size >= sizeof(hash_key))
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break;
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size += snprintf(& hash_key[size], sizeof(hash_key) - size,
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"%p", (void *) key->fields.structure[i].type);
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/* casting pointer to uintptr_t */
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hash = (hash * 13 ) + (uintptr_t) key->fields.structure[i].type;
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}
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return hash_table_string_hash(& hash_key);
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if (sizeof(hash) == 8)
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retval = (hash & 0xffffffff) ^ ((uint64_t) hash >> 32);
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else
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retval = hash;
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return retval;
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}
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