From: Ard Biesheuvel ardb@kernel.org
[ Upstream commit e1df73e2d18b3b7d66f2ec38d81d9566b3a7fb21 ]
The EFI stub uses a per-architecture #define for the minimum base and size alignment of page allocations, which is set to 4 KB for all architecures except arm64, which uses 64 KB, to ensure that allocations can always be (un)mapped efficiently, regardless of the page size used by the kernel proper, which could be a kexec'ee
The API wrappers around page based allocations assume that this alignment is always taken into account, and so efi_free() will also round up its size argument to EFI_ALLOC_ALIGN.
Currently, efi_random_alloc() does not honour this alignment for the allocated size, and so freeing such an allocation may result in unrelated memory to be freed, potentially leading to issues after boot. So let's round up size in efi_random_alloc() as well.
Fixes: 2ddbfc81eac84a29 ("efi: stub: add implementation of efi_random_alloc()") Signed-off-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/firmware/efi/libstub/randomalloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c index 4578f59e160c..6200dfa650f5 100644 --- a/drivers/firmware/efi/libstub/randomalloc.c +++ b/drivers/firmware/efi/libstub/randomalloc.c @@ -74,6 +74,8 @@ efi_status_t efi_random_alloc(unsigned long size, if (align < EFI_ALLOC_ALIGN) align = EFI_ALLOC_ALIGN;
+ size = round_up(size, EFI_ALLOC_ALIGN); + /* count the suitable slots in each memory map entry */ for (map_offset = 0; map_offset < map_size; map_offset += desc_size) { efi_memory_desc_t *md = (void *)memory_map + map_offset; @@ -109,7 +111,7 @@ efi_status_t efi_random_alloc(unsigned long size, }
target = round_up(md->phys_addr, align) + target_slot * align; - pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE; + pages = size / EFI_PAGE_SIZE;
status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS, EFI_LOADER_DATA, pages, &target);