From: Gen Zhang <blackgod016574@xxxxxxxxx> commit 4e78921ba4dd0aca1cc89168f45039add4183f8e upstream. The old_memmap flow in efi_call_phys_prolog() performs numerous memory allocations, and either does not check for failure at all, or it does but fails to propagate it back to the caller, which may end up calling into the firmware with an incomplete 1:1 mapping. So let's fix this by returning NULL from efi_call_phys_prolog() on memory allocation failures only, and by handling this condition in the caller. Also, clean up any half baked sets of page tables that we may have created before returning with a NULL return value. Note that any failure at this level will trigger a panic() two levels up, so none of this makes a huge difference, but it is a nice cleanup nonetheless. [ardb: update commit log, add efi_call_phys_epilog() call on error path] Signed-off-by: Gen Zhang <blackgod016574@xxxxxxxxx> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Rob Bradford <robert.bradford@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: linux-efi@xxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/20190525112559.7917-2-ard.biesheuvel@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Srivatsa S. Bhat (VMware) <srivatsa@xxxxxxxxxxxxx> --- arch/x86/platform/efi/efi.c | 2 ++ arch/x86/platform/efi/efi_64.c | 9 ++++++--- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 9061bab..353019d 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -86,6 +86,8 @@ static efi_status_t __init phys_efi_set_virtual_address_map( pgd_t *save_pgd; save_pgd = efi_call_phys_prolog(); + if (!save_pgd) + return EFI_ABORTED; /* Disable interrupts around EFI calls: */ local_irq_save(flags); diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index ee5d08f..dfc809b 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -84,13 +84,15 @@ pgd_t * __init efi_call_phys_prolog(void) if (!efi_enabled(EFI_OLD_MEMMAP)) { efi_switch_mm(&efi_mm); - return NULL; + return efi_mm.pgd; } early_code_mapping_set_exec(1); n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE); save_pgd = kmalloc_array(n_pgds, sizeof(*save_pgd), GFP_KERNEL); + if (!save_pgd) + return NULL; /* * Build 1:1 identity mapping for efi=old_map usage. Note that @@ -138,10 +140,11 @@ pgd_t * __init efi_call_phys_prolog(void) pgd_offset_k(pgd * PGDIR_SIZE)->pgd &= ~_PAGE_NX; } -out: __flush_tlb_all(); - return save_pgd; +out: + efi_call_phys_epilog(save_pgd); + return NULL; } void __init efi_call_phys_epilog(pgd_t *save_pgd)
