From 510cd0c36a3beb0907bdbd31a48b71abdddb44a7 Mon Sep 17 00:00:00 2001 From: Peter Jones Date: Wed, 7 Dec 2016 16:20:10 -0500 Subject: [PATCH 2/4] efi: efi_map_region(): traceback if we try to map invalid sized regions Some machines, such as the Lenovo ThinkPad W541 with firmware GNET80WW (2.28), include memory map entries with phys_addr=0x0 and num_pages=0. We shouldn't ever try to map these errors, so if we get as far as efi_map_region(), show a traceback. This additionally makes should_map_region() say not to map them, but I fixed both places in case another caller of efi_map_region() ever arises in the future. Signed-off-by: Peter Jones --- arch/x86/platform/efi/efi.c | 4 ++++ arch/x86/platform/efi/efi_64.c | 19 ++++++++++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 181c915..bf32454 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -707,6 +707,10 @@ static bool should_map_region(efi_memory_desc_t *md) if (IS_ENABLED(CONFIG_X86_32)) return false; + if (md->num_pages == 0 || + md->num_pages >= (((u64)-1LL) >> EFI_PAGE_SHIFT)) + return false; + /* * Map all of RAM so that we can access arguments in the 1:1 * mapping when making EFI runtime calls. diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index de12d9f..f80de01 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -283,11 +283,24 @@ static void __init __map_region(efi_memory_desc_t *md, u64 va) void __init efi_map_region(efi_memory_desc_t *md) { - unsigned long size = md->num_pages << PAGE_SHIFT; + u64 size = md->num_pages << PAGE_SHIFT; u64 pa = md->phys_addr; - if (efi_enabled(EFI_OLD_MEMMAP)) - return old_map_region(md); + /* + * hah hah the system firmware is having a good one on us + */ + if (md->num_pages == 0 || + md->num_pages >= (((u64)-1LL) >> EFI_PAGE_SHIFT)) { + pr_err("memmap from %p to %p is unreasonable. Not mapping it.\n", + (void *)pa, (void *)(pa+size)); + WARN_ON(1); + return; + } + + if (efi_enabled(EFI_OLD_MEMMAP)) { + old_map_region(md); + return; + } /* * Make sure the 1:1 mappings are present as a catch-all for b0rked -- 2.9.3