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loader: fix heap overflow when registry path exceeds reg_data buffer #1916

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loader: fix heap overflow when registry path exceeds reg_data buffer #1916

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39 changes: 26 additions & 13 deletions loader/loader_windows.c
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Original file line number Diff line number Diff line change
Expand Up @@ -131,6 +131,10 @@ bool windows_add_json_entry(const struct loader_instance *inst,
}

if (NULL == *reg_data) {
// json_size is the registry value size and can be larger than the default buffer, so grow until it fits.
while (json_size + 1 > *total_size) {
*total_size *= 2;
}
*reg_data = loader_instance_heap_alloc(inst, *total_size, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
if (NULL == *reg_data) {
loader_log(inst, VULKAN_LOADER_ERROR_BIT, 0,
Expand All @@ -140,24 +144,28 @@ bool windows_add_json_entry(const struct loader_instance *inst,
}
*reg_data[0] = '\0';
} else if (strlen(*reg_data) + json_size + 1 > *total_size) {
void *new_ptr =
loader_instance_heap_realloc(inst, *reg_data, *total_size, *total_size * 2, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
DWORD new_size = *total_size;
while (strlen(*reg_data) + json_size + 1 > new_size) {
new_size *= 2;
}
void *new_ptr = loader_instance_heap_realloc(inst, *reg_data, *total_size, new_size, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
if (NULL == new_ptr) {
loader_log(inst, VULKAN_LOADER_ERROR_BIT, 0,
"windows_add_json_entry: Failed to reallocate space for registry value of size %ld for key %s",
*total_size * 2, json_path);
"windows_add_json_entry: Failed to reallocate space for registry value of size %ld for key %s", new_size,
json_path);
*result = VK_ERROR_OUT_OF_HOST_MEMORY;
return false;
}
*reg_data = new_ptr;
*total_size *= 2;
*total_size = new_size;
}

for (char *curr_filename = json_path; curr_filename[0] != '\0'; curr_filename += strlen(curr_filename) + 1) {
if (strlen(*reg_data) == 0) {
(void)snprintf(*reg_data, json_size + 1, "%s", curr_filename);
size_t cur_len = strlen(*reg_data);
if (cur_len == 0) {
(void)snprintf(*reg_data, *total_size, "%s", curr_filename);
} else {
(void)snprintf(*reg_data + strlen(*reg_data), json_size + 2, "%c%s", PATH_SEPARATOR, curr_filename);
(void)snprintf(*reg_data + cur_len, *total_size - cur_len, "%c%s", PATH_SEPARATOR, curr_filename);
}
loader_log(inst, VULKAN_LOADER_INFO_BIT, 0, "%s: Located json file \"%s\" from PnP registry: %s", __FUNCTION__,
curr_filename, key_name);
Expand Down Expand Up @@ -445,19 +453,23 @@ VkResult windows_get_registry_files(const struct loader_instance *inst, char *lo
}
*reg_data[0] = '\0';
} else if (strlen(*reg_data) + name_size + 1 > *reg_data_size) {
void *new_ptr = loader_instance_heap_realloc(inst, *reg_data, *reg_data_size, *reg_data_size * 2,
DWORD new_size = *reg_data_size;
while (strlen(*reg_data) + name_size + 1 > new_size) {
new_size *= 2;
}
void *new_ptr = loader_instance_heap_realloc(inst, *reg_data, *reg_data_size, new_size,
VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
if (NULL == new_ptr) {
loader_log(
inst, VULKAN_LOADER_ERROR_BIT | log_target_flag, 0,
"windows_get_registry_files: Failed to reallocate space for registry value of size %ld for key %s",
*reg_data_size * 2, name);
new_size, name);
RegCloseKey(key);
result = VK_ERROR_OUT_OF_HOST_MEMORY;
goto out;
}
*reg_data = new_ptr;
*reg_data_size *= 2;
*reg_data_size = new_size;
}

// We've now found a json file. If this is an ICD, we still need to check if there is actually a device
Expand Down Expand Up @@ -516,7 +528,7 @@ VkResult windows_get_registry_files(const struct loader_instance *inst, char *lo

if (strlen(*reg_data) == 0) {
// The list is emtpy. Add the first entry.
(void)snprintf(*reg_data, name_size + 1, "%s", name);
(void)snprintf(*reg_data, *reg_data_size, "%s", name);
found = true;
} else {
// At this point the reg_data variable contains other JSON paths, likely from the PNP/device section
Expand All @@ -536,7 +548,8 @@ VkResult windows_get_registry_files(const struct loader_instance *inst, char *lo
// Only skip if we are adding a driver and a duplicate was found
if (!is_driver || (is_driver && foundDuplicate == false)) {
// Add the new entry to the list.
(void)snprintf(*reg_data + strlen(*reg_data), name_size + 2, "%c%s", PATH_SEPARATOR, name);
size_t cur_len = strlen(*reg_data);
(void)snprintf(*reg_data + cur_len, *reg_data_size - cur_len, "%c%s", PATH_SEPARATOR, name);
found = true;
} else {
loader_log(
Expand Down
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