2012-10-25 01:51:41

by Seiji Aguchi

Subject: [PATCH v2 1/5] 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: Seiji Aguchi <[email protected]>
---
drivers/firmware/efivars.c | 18 ++++++++++++++++++
include/linux/efi.h | 1 +
2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index d10c987..37ac21a 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -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;
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8670eb1..c47ec36 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -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 {
-- 1.7.1

2012-10-25 18:56:37

by Mike Waychison

Subject: Re: [PATCH v2 1/5] efi_pstore: Check remaining space with QueryVariableInfo() before writing data

Acked-by: Mike Waychison <[email protected]>

On Wed, Oct 24, 2012 at 6:51 PM, Seiji Aguchi <[email protected]> wrote:
> [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: Seiji Aguchi <[email protected]>
> ---
> drivers/firmware/efivars.c | 18 ++++++++++++++++++
> include/linux/efi.h | 1 +
> 2 files changed, 19 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
> index d10c987..37ac21a 100644
> --- a/drivers/firmware/efivars.c
> +++ b/drivers/firmware/efivars.c
> @@ -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;
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 8670eb1..c47ec36 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -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 {
> -- 1.7.1