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efi_loader: fix efi_dp_find_obj()

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efi_dp_find_obj() should not return any handle with a partially matching
device path but the handle with the maximum matching device path.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
This commit is contained in:
Heinrich Schuchardt 2022-03-04 08:20:00 +01:00
parent 8399488672
commit c409593d08
2 changed files with 63 additions and 51 deletions
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110
lib/efi_loader/efi_device_path.c
View file

@ -159,69 +159,81 @@ struct efi_device_path *efi_dp_shorten(struct efi_device_path *dp)
return dp;
}
static struct efi_object *find_obj(struct efi_device_path *dp, bool short_path,
struct efi_device_path **rem)
/**
* find_handle() - find handle by device path
*
* If @rem is provided, the handle with the longest partial match is returned.
*
* @dp: device path to search
* @short_path: use short form device path for matching
* @rem: pointer to receive remaining device path
* Return: matching handle
*/
static efi_handle_t find_handle(struct efi_device_path *dp, bool short_path,
struct efi_device_path **rem)
{
struct efi_object *efiobj;
efi_uintn_t dp_size = efi_dp_instance_size(dp);
efi_handle_t handle, best_handle = NULL;
efi_uintn_t len, best_len = 0;
list_for_each_entry(efiobj, &efi_obj_list, link) {
len = efi_dp_instance_size(dp);
list_for_each_entry(handle, &efi_obj_list, link) {
struct efi_handler *handler;
struct efi_device_path *obj_dp;
struct efi_device_path *dp_current;
efi_uintn_t len_current;
efi_status_t ret;
ret = efi_search_protocol(efiobj,
&efi_guid_device_path, &handler);
ret = efi_search_protocol(handle, &efi_guid_device_path,
&handler);
if (ret != EFI_SUCCESS)
continue;
obj_dp = handler->protocol_interface;
do {
if (efi_dp_match(dp, obj_dp) == 0) {
if (rem) {
/*
* Allow partial matches, but inform
* the caller.
*/
*rem = ((void *)dp) +
efi_dp_instance_size(obj_dp);
return efiobj;
} else {
/* Only return on exact matches */
if (efi_dp_instance_size(obj_dp) ==
dp_size)
return efiobj;
}
}
obj_dp = efi_dp_shorten(efi_dp_next(obj_dp));
} while (short_path && obj_dp);
dp_current = handler->protocol_interface;
if (short_path) {
dp_current = efi_dp_shorten(dp_current);
if (!dp_current)
continue;
}
len_current = efi_dp_instance_size(dp_current);
if (rem) {
if (len_current < len)
continue;
} else {
if (len_current != len)
continue;
}
if (memcmp(dp_current, dp, len))
continue;
if (!rem)
return handle;
if (len_current > best_len) {
best_len = len_current;
best_handle = handle;
*rem = (void*)((u8 *)dp + len_current);
}
}
return NULL;
return best_handle;
}
/*
* Find an efiobj from device-path, if 'rem' is not NULL, returns the
* remaining part of the device path after the matched object.
/**
* efi_dp_find_obj() - find handle by device path
*
* If @rem is provided, the handle with the longest partial match is returned.
*
* @dp: device path to search
* @rem: pointer to receive remaining device path
* Return: matching handle
*/
struct efi_object *efi_dp_find_obj(struct efi_device_path *dp,
struct efi_device_path **rem)
efi_handle_t efi_dp_find_obj(struct efi_device_path *dp,
struct efi_device_path **rem)
{
struct efi_object *efiobj;
efi_handle_t handle;
/* Search for an exact match first */
efiobj = find_obj(dp, false, NULL);
handle = find_handle(dp, false, rem);
if (!handle)
/* Match short form device path */
handle = find_handle(dp, true, rem);
/* Then for a fuzzy match */
if (!efiobj)
efiobj = find_obj(dp, false, rem);
/* And now for a fuzzy short match */
if (!efiobj)
efiobj = find_obj(dp, true, rem);
return efiobj;
return handle;
}
/*