Commit-ID: 68d929862e29a8b52a7f2f2f86a0600423b093cd Gitweb: http://git.kernel.org/tip/68d929862e29a8b52a7f2f2f86a0600423b093cd Author: Matthew Garrett <matthew.garrett@xxxxxxxxxx> AuthorDate: Sat, 2 Mar 2013 19:40:17 -0500 Committer: Matt Fleming <matt.fleming@xxxxxxxxx> CommitDate: Wed, 6 Mar 2013 14:43:29 +0000 efi: be more paranoid about available space when creating variables UEFI variables are typically stored in flash. For various reasons, avaiable space is typically not reclaimed immediately upon the deletion of a variable - instead, the system will garbage collect during initialisation after a reboot. Some systems appear to handle this garbage collection extremely poorly, failing if more than 50% of the system flash is in use. This can result in the machine refusing to boot. The safest thing to do for the moment is to forbid writes if they'd end up using more than half of the storage space. We can make this more finegrained later if we come up with a method for identifying the broken machines. Signed-off-by: Matthew Garrett <matthew.garrett@xxxxxxxxxx> Cc: Josh Boyer <jwboyer@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx> --- drivers/firmware/efivars.c | 106 +++++++++++++++++++++++++++++++++------------ 1 file changed, 79 insertions(+), 27 deletions(-) diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index 7320bf8..0d50497 100644 --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -426,6 +426,44 @@ get_var_data(struct efivars *efivars, struct efi_variable *var) return status; } +static efi_status_t +check_var_size_locked(struct efivars *efivars, u32 attributes, + unsigned long size) +{ + u64 storage_size, remaining_size, max_size; + efi_status_t status; + const struct efivar_operations *fops = efivars->ops; + + if (!efivars->ops->query_variable_info) + return EFI_UNSUPPORTED; + + status = fops->query_variable_info(attributes, &storage_size, + &remaining_size, &max_size); + + if (status != EFI_SUCCESS) + return status; + + if (!storage_size || size > remaining_size || size > max_size || + (remaining_size - size) < (storage_size / 2)) + return EFI_OUT_OF_RESOURCES; + + return status; +} + + +static efi_status_t +check_var_size(struct efivars *efivars, u32 attributes, unsigned long size) +{ + efi_status_t status; + unsigned long flags; + + spin_lock_irqsave(&efivars->lock, flags); + status = check_var_size_locked(efivars, attributes, size); + spin_unlock_irqrestore(&efivars->lock, flags); + + return status; +} + static ssize_t efivar_guid_read(struct efivar_entry *entry, char *buf) { @@ -547,11 +585,16 @@ efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count) } spin_lock_irq(&efivars->lock); - status = efivars->ops->set_variable(new_var->VariableName, - &new_var->VendorGuid, - new_var->Attributes, - new_var->DataSize, - new_var->Data); + + status = check_var_size_locked(efivars, new_var->Attributes, + new_var->DataSize + utf16_strsize(new_var->VariableName, 1024)); + + if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED) + status = efivars->ops->set_variable(new_var->VariableName, + &new_var->VendorGuid, + new_var->Attributes, + new_var->DataSize, + new_var->Data); spin_unlock_irq(&efivars->lock); @@ -702,8 +745,7 @@ static ssize_t efivarfs_file_write(struct file *file, u32 attributes; struct inode *inode = file->f_mapping->host; unsigned long datasize = count - sizeof(attributes); - unsigned long newdatasize; - u64 storage_size, remaining_size, max_size; + unsigned long newdatasize, varsize; ssize_t bytes = 0; if (count < sizeof(attributes)) @@ -722,28 +764,18 @@ static ssize_t efivarfs_file_write(struct file *file, * amounts of memory. Pick a default size of 64K if * QueryVariableInfo() isn't supported by the firmware. */ - spin_lock_irq(&efivars->lock); - if (!efivars->ops->query_variable_info) - status = EFI_UNSUPPORTED; - else { - const struct efivar_operations *fops = efivars->ops; - status = fops->query_variable_info(attributes, &storage_size, - &remaining_size, &max_size); - } - - spin_unlock_irq(&efivars->lock); + varsize = datasize + utf16_strsize(var->var.VariableName, 1024); + status = check_var_size(efivars, attributes, varsize); if (status != EFI_SUCCESS) { if (status != EFI_UNSUPPORTED) return efi_status_to_err(status); - remaining_size = 65536; + if (datasize > 65536) + return -ENOSPC; } - if (datasize > remaining_size) - return -ENOSPC; - data = kmalloc(datasize, GFP_KERNEL); if (!data) return -ENOMEM; @@ -765,6 +797,19 @@ static ssize_t efivarfs_file_write(struct file *file, */ spin_lock_irq(&efivars->lock); + /* + * Ensure that the available space hasn't shrunk below the safe level + */ + + status = check_var_size_locked(efivars, attributes, varsize); + + if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED) { + spin_unlock_irq(&efivars->lock); + kfree(data); + + return efi_status_to_err(status); + } + status = efivars->ops->set_variable(var->var.VariableName, &var->var.VendorGuid, attributes, datasize, @@ -1345,7 +1390,6 @@ static int efi_pstore_write(enum pstore_type_id type, efi_guid_t vendor = LINUX_EFI_CRASH_GUID; struct efivars *efivars = psi->data; int i, ret = 0; - u64 storage_space, remaining_space, max_variable_size; efi_status_t status = EFI_NOT_FOUND; unsigned long flags; @@ -1365,11 +1409,11 @@ static int efi_pstore_write(enum pstore_type_id type, * 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) { + + status = check_var_size_locked(efivars, PSTORE_EFI_ATTRIBUTES, + size + DUMP_NAME_LEN * 2); + + if (status) { spin_unlock_irqrestore(&efivars->lock, flags); *id = part; return -ENOSPC; @@ -1544,6 +1588,14 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj, return -EINVAL; } + status = check_var_size_locked(efivars, new_var->Attributes, + new_var->DataSize + utf16_strsize(new_var->VariableName, 1024)); + + if (status && status != EFI_UNSUPPORTED) { + spin_unlock_irq(&efivars->lock); + return efi_status_to_err(status); + } + /* now *really* create the variable via EFI */ status = efivars->ops->set_variable(new_var->VariableName, &new_var->VendorGuid, -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html