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authorMatt Fleming <matt.fleming@intel.com>2012-11-09 22:02:56 +0100
committerMatt Fleming <matt.fleming@intel.com>2012-11-13 13:33:21 +0100
commit89d16665d388837b30972081d97b814be26d68a2 (patch)
tree0fd95e1e9d6886c27e7d9b7eed7464cd2e22988d /drivers/firmware/efivars.c
parentefivarfs: Fix return value of efivarfs_file_write() (diff)
downloadlinux-89d16665d388837b30972081d97b814be26d68a2.tar.xz
linux-89d16665d388837b30972081d97b814be26d68a2.zip
efivarfs: Use query_variable_info() to limit kmalloc()
We don't want someone who can write EFI variables to be able to allocate arbitrarily large amounts of memory, so cap it to something sensible like the amount of free space for EFI variables. Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com> Cc: Matthew Garrett <mjg@redhat.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Diffstat (limited to 'drivers/firmware/efivars.c')
-rw-r--r--drivers/firmware/efivars.c43
1 files changed, 34 insertions, 9 deletions
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 9ac934018bba..d6b8d2f628fa 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -694,28 +694,51 @@ static ssize_t efivarfs_file_write(struct file *file,
struct inode *inode = file->f_mapping->host;
unsigned long datasize = count - sizeof(attributes);
unsigned long newdatasize;
+ u64 storage_size, remaining_size, max_size;
ssize_t bytes = 0;
if (count < sizeof(attributes))
return -EINVAL;
- data = kmalloc(datasize, GFP_KERNEL);
+ if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
+ return -EFAULT;
- if (!data)
- return -ENOMEM;
+ if (attributes & ~(EFI_VARIABLE_MASK))
+ return -EINVAL;
efivars = var->efivars;
- if (copy_from_user(&attributes, userbuf, sizeof(attributes))) {
- bytes = -EFAULT;
- goto out;
+ /*
+ * Ensure that the user can't allocate arbitrarily large
+ * amounts of memory. Pick a default size of 64K if
+ * QueryVariableInfo() isn't supported by the firmware.
+ */
+ spin_lock(&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);
}
- if (attributes & ~(EFI_VARIABLE_MASK)) {
- bytes = -EINVAL;
- goto out;
+ spin_unlock(&efivars->lock);
+
+ if (status != EFI_SUCCESS) {
+ if (status != EFI_UNSUPPORTED)
+ return efi_status_to_err(status);
+
+ remaining_size = 65536;
}
+ if (datasize > remaining_size)
+ return -ENOSPC;
+
+ data = kmalloc(datasize, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
if (copy_from_user(data, userbuf + sizeof(attributes), datasize)) {
bytes = -EFAULT;
goto out;
@@ -1709,6 +1732,8 @@ 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;