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efi: mokvar-table: fix some issues in new code

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Fix a couple of issues in the new mokvar-table handling code, as
pointed out by Arvind and Boris:
- don't bother checking the end of the physical region against the start
  address of the mokvar table,
- ensure that we enter the loop with err = -EINVAL,
- replace size_t with unsigned long to appease pedantic type equality
  checks.

Reviewed-by: Arvind Sankar <nivedita@alum.mit.edu>
Reviewed-by: Lenny Szubowicz <lszubowi@redhat.com>
Tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Ard Biesheuvel 2020-09-24 17:58:22 +02:00
parent 612b5d506d
commit b89114cd01
1 changed files with 11 additions and 14 deletions
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25
drivers/firmware/efi/mokvar-table.c
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@ -98,15 +98,14 @@ static struct kobject *mokvar_kobj;
void __init efi_mokvar_table_init(void) void __init efi_mokvar_table_init(void)
{ {
efi_memory_desc_t md; efi_memory_desc_t md;
u64 end_pa;
void *va = NULL; void *va = NULL;
size_t cur_offset = 0; unsigned long cur_offset = 0;
size_t offset_limit; unsigned long offset_limit;
size_t map_size = 0; unsigned long map_size = 0;
size_t map_size_needed = 0; unsigned long map_size_needed = 0;
size_t size; unsigned long size;
struct efi_mokvar_table_entry *mokvar_entry; struct efi_mokvar_table_entry *mokvar_entry;
int err = -EINVAL; int err;
if (!efi_enabled(EFI_MEMMAP)) if (!efi_enabled(EFI_MEMMAP))
return; return;
@ -122,18 +121,16 @@ void __init efi_mokvar_table_init(void)
pr_warn("EFI MOKvar config table is not within the EFI memory map\n"); pr_warn("EFI MOKvar config table is not within the EFI memory map\n");
return; return;
} }
end_pa = efi_mem_desc_end(&md);
if (efi.mokvar_table >= end_pa) { offset_limit = efi_mem_desc_end(&md) - efi.mokvar_table;
pr_err("EFI memory descriptor containing MOKvar config table is invalid\n");
return;
}
offset_limit = end_pa - efi.mokvar_table;
/* /*
* Validate the MOK config table. Since there is no table header * Validate the MOK config table. Since there is no table header
* from which we could get the total size of the MOK config table, * from which we could get the total size of the MOK config table,
* we compute the total size as we validate each variably sized * we compute the total size as we validate each variably sized
* entry, remapping as necessary. * entry, remapping as necessary.
*/ */
err = -EINVAL;
while (cur_offset + sizeof(*mokvar_entry) <= offset_limit) { while (cur_offset + sizeof(*mokvar_entry) <= offset_limit) {
mokvar_entry = va + cur_offset; mokvar_entry = va + cur_offset;
map_size_needed = cur_offset + sizeof(*mokvar_entry); map_size_needed = cur_offset + sizeof(*mokvar_entry);
@ -150,7 +147,7 @@ void __init efi_mokvar_table_init(void)
offset_limit); offset_limit);
va = early_memremap(efi.mokvar_table, map_size); va = early_memremap(efi.mokvar_table, map_size);
if (!va) { if (!va) {
pr_err("Failed to map EFI MOKvar config table pa=0x%lx, size=%zu.\n", pr_err("Failed to map EFI MOKvar config table pa=0x%lx, size=%lu.\n",
efi.mokvar_table, map_size); efi.mokvar_table, map_size);
return; return;
} }