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Commit d80a361d authored by Seiji Aguchi's avatar Seiji Aguchi Committed by Tony Luck
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efi_pstore: Check remaining space with QueryVariableInfo() before writing data 

[Issue]

As discussed in a thread below, Running out of space in EFI isn't a well-tested scenario.
And we wouldn't expect all firmware to handle it gracefully.
http://marc.info/?l=linux-kernel&m=134305325801789&w=2



On the other hand, current efi_pstore doesn't check a remaining space of storage at writing time.
Therefore, efi_pstore may not work if it tries to write a large amount of data.

[Patch Description]

To avoid handling the situation above, this patch checks if there is a space enough to log with
QueryVariableInfo() before writing data.

Signed-off-by: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
Acked-by: default avatarMike Waychison <mikew@google.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 9489e9dc

drivers/firmware/efivars.c

+18 −0
Original line number Diff line number Diff line
@@ -707,12 +707,29 @@ static int efi_pstore_write(enum pstore_type_id type, 
	struct efivars *efivars = psi->data;

	struct efivar_entry *entry, *found = NULL;

	int i, ret = 0;

	u64 storage_space, remaining_space, max_variable_size;

	efi_status_t status = EFI_NOT_FOUND;



	sprintf(stub_name, "dump-type%u-%u-", type, part);

	sprintf(name, "%s%lu", stub_name, get_seconds());



	spin_lock(&efivars->lock);



	/*

	 * Check if there is a space enough to log.

	 * size: a size of logging data

	 * DUMP_NAME_LEN * 2: a maximum size of variable name

	 */

	status = efivars->ops->query_variable_info(PSTORE_EFI_ATTRIBUTES,

						   &storage_space,

						   &remaining_space,

						   &max_variable_size);

	if (status || remaining_space < size + DUMP_NAME_LEN * 2) {

		spin_unlock(&efivars->lock);

		*id = part;

		return -ENOSPC;

	}



	for (i = 0; i < DUMP_NAME_LEN; i++)

		efi_name[i] = stub_name[i];
@@ -1237,6 +1254,7 @@ efivars_init(void) 
	ops.get_variable = efi.get_variable;

	ops.set_variable = efi.set_variable;

	ops.get_next_variable = efi.get_next_variable;

	ops.query_variable_info = efi.query_variable_info;

	error = register_efivars(&__efivars, &ops, efi_kobj);

	if (error)

		goto err_put;

include/linux/efi.h

+1 −0
Original line number Diff line number Diff line
@@ -643,6 +643,7 @@ struct efivar_operations { 
	efi_get_variable_t *get_variable;

	efi_get_next_variable_t *get_next_variable;

	efi_set_variable_t *set_variable;

	efi_query_variable_info_t *query_variable_info;

};



struct efivars {