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    Subject[PATCH 4.9 26/87] efi: Avoid potential crashes, fix the struct efi_pci_io_protocol_32 definition for mixed mode
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

    commit 0b3225ab9407f557a8e20f23f37aa7236c10a9b1 upstream.

    Mixed mode allows a kernel built for x86_64 to interact with 32-bit
    EFI firmware, but requires us to define all struct definitions carefully
    when it comes to pointer sizes.

    'struct efi_pci_io_protocol_32' currently uses a 'void *' for the
    'romimage' field, which will be interpreted as a 64-bit field
    on such kernels, potentially resulting in bogus memory references
    and subsequent crashes.

    Tested-by: Hans de Goede <hdegoede@redhat.com>
    Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    Cc: <stable@vger.kernel.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Matt Fleming <matt@codeblueprint.co.uk>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-efi@vger.kernel.org
    Link: http://lkml.kernel.org/r/20180504060003.19618-13-ard.biesheuvel@linaro.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/boot/compressed/eboot.c | 6 ++++--
    include/linux/efi.h | 8 ++++----
    2 files changed, 8 insertions(+), 6 deletions(-)

    --- a/arch/x86/boot/compressed/eboot.c
    +++ b/arch/x86/boot/compressed/eboot.c
    @@ -330,7 +330,8 @@ __setup_efi_pci32(efi_pci_io_protocol_32
    if (status != EFI_SUCCESS)
    goto free_struct;

    - memcpy(rom->romdata, pci->romimage, pci->romsize);
    + memcpy(rom->romdata, (void *)(unsigned long)pci->romimage,
    + pci->romsize);
    return status;

    free_struct:
    @@ -436,7 +437,8 @@ __setup_efi_pci64(efi_pci_io_protocol_64
    if (status != EFI_SUCCESS)
    goto free_struct;

    - memcpy(rom->romdata, pci->romimage, pci->romsize);
    + memcpy(rom->romdata, (void *)(unsigned long)pci->romimage,
    + pci->romsize);
    return status;

    free_struct:
    --- a/include/linux/efi.h
    +++ b/include/linux/efi.h
    @@ -380,8 +380,8 @@ typedef struct {
    u32 attributes;
    u32 get_bar_attributes;
    u32 set_bar_attributes;
    - uint64_t romsize;
    - void *romimage;
    + u64 romsize;
    + u32 romimage;
    } efi_pci_io_protocol_32;

    typedef struct {
    @@ -400,8 +400,8 @@ typedef struct {
    u64 attributes;
    u64 get_bar_attributes;
    u64 set_bar_attributes;
    - uint64_t romsize;
    - void *romimage;
    + u64 romsize;
    + u64 romimage;
    } efi_pci_io_protocol_64;

    typedef struct {

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