On Mon, Jul 28, 2014 at 02:21:53PM +0100, Michael Brown wrote:
> commit c7fb93ec51d462ec3540a729ba446663c26a0505 upstream
>
Thanks, I'll use this backport for the 3.11 kernel as well.
Cheers,
--
Luís
> The PE/COFF headers currently describe only the initialised-data
> portions of the image, and result in no space being allocated for the
> uninitialised-data portions. Consequently, the EFI boot stub will end
> up overwriting unexpected areas of memory, with unpredictable results.
>
> Fix by including a .bss section in the PE/COFF headers (functionally
> equivalent to the init_size field in the bzImage header).
>
> Signed-off-by: Michael Brown <mbrown@xxxxxxxxxxxxxxxx>
> Cc: linux-efi@xxxxxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> arch/x86/boot/header.S | 26 ++++++++++++++++++++++----
> arch/x86/boot/tools/build.c | 37 ++++++++++++++++++++++++++++++-------
> 2 files changed, 52 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
> index ec3b8ba..04da6c2 100644
> --- a/arch/x86/boot/header.S
> +++ b/arch/x86/boot/header.S
> @@ -91,10 +91,9 @@ bs_die:
>
> .section ".bsdata", "a"
> bugger_off_msg:
> - .ascii "Direct floppy boot is not supported. "
> - .ascii "Use a boot loader program instead.\r\n"
> + .ascii "Use a boot loader.\r\n"
> .ascii "\n"
> - .ascii "Remove disk and press any key to reboot ...\r\n"
> + .ascii "Remove disk and press any key to reboot...\r\n"
> .byte 0
>
> #ifdef CONFIG_EFI_STUB
> @@ -108,7 +107,7 @@ coff_header:
> #else
> .word 0x8664 # x86-64
> #endif
> - .word 3 # nr_sections
> + .word 4 # nr_sections
> .long 0 # TimeDateStamp
> .long 0 # PointerToSymbolTable
> .long 1 # NumberOfSymbols
> @@ -250,6 +249,25 @@ section_table:
> .word 0 # NumberOfLineNumbers
> .long 0x60500020 # Characteristics (section flags)
>
> + #
> + # The offset & size fields are filled in by build.c.
> + #
> + .ascii ".bss"
> + .byte 0
> + .byte 0
> + .byte 0
> + .byte 0
> + .long 0
> + .long 0x0
> + .long 0 # Size of initialized data
> + # on disk
> + .long 0x0
> + .long 0 # PointerToRelocations
> + .long 0 # PointerToLineNumbers
> + .word 0 # NumberOfRelocations
> + .word 0 # NumberOfLineNumbers
> + .long 0xc8000080 # Characteristics (section flags)
> +
> #endif /* CONFIG_EFI_STUB */
>
> # Kernel attributes; used by setup. This is part 1 of the
> diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
> index 8e15b22..3dafaeb 100644
> --- a/arch/x86/boot/tools/build.c
> +++ b/arch/x86/boot/tools/build.c
> @@ -142,7 +142,7 @@ static void usage(void)
>
> #ifdef CONFIG_EFI_STUB
>
> -static void update_pecoff_section_header(char *section_name, u32 offset, u32 size)
> +static void update_pecoff_section_header_fields(char *section_name, u32 vma, u32 size, u32 datasz, u32 offset)
> {
> unsigned int pe_header;
> unsigned short num_sections;
> @@ -163,10 +163,10 @@ static void update_pecoff_section_header(char *section_name, u32 offset, u32 siz
> put_unaligned_le32(size, section + 0x8);
>
> /* section header vma field */
> - put_unaligned_le32(offset, section + 0xc);
> + put_unaligned_le32(vma, section + 0xc);
>
> /* section header 'size of initialised data' field */
> - put_unaligned_le32(size, section + 0x10);
> + put_unaligned_le32(datasz, section + 0x10);
>
> /* section header 'file offset' field */
> put_unaligned_le32(offset, section + 0x14);
> @@ -178,6 +178,11 @@ static void update_pecoff_section_header(char *section_name, u32 offset, u32 siz
> }
> }
>
> +static void update_pecoff_section_header(char *section_name, u32 offset, u32 size)
> +{
> + update_pecoff_section_header_fields(section_name, offset, size, size, offset);
> +}
> +
> static void update_pecoff_setup_and_reloc(unsigned int size)
> {
> u32 setup_offset = 0x200;
> @@ -202,9 +207,6 @@ static void update_pecoff_text(unsigned int text_start, unsigned int file_sz)
>
> pe_header = get_unaligned_le32(&buf[0x3c]);
>
> - /* Size of image */
> - put_unaligned_le32(file_sz, &buf[pe_header + 0x50]);
> -
> /*
> * Size of code: Subtract the size of the first sector (512 bytes)
> * which includes the header.
> @@ -219,6 +221,22 @@ static void update_pecoff_text(unsigned int text_start, unsigned int file_sz)
> update_pecoff_section_header(".text", text_start, text_sz);
> }
>
> +static void update_pecoff_bss(unsigned int file_sz, unsigned int init_sz)
> +{
> + unsigned int pe_header;
> + unsigned int bss_sz = init_sz - file_sz;
> +
> + pe_header = get_unaligned_le32(&buf[0x3c]);
> +
> + /* Size of uninitialized data */
> + put_unaligned_le32(bss_sz, &buf[pe_header + 0x24]);
> +
> + /* Size of image */
> + put_unaligned_le32(init_sz, &buf[pe_header + 0x50]);
> +
> + update_pecoff_section_header_fields(".bss", file_sz, bss_sz, 0, 0);
> +}
> +
> #endif /* CONFIG_EFI_STUB */
>
>
> @@ -270,6 +288,9 @@ int main(int argc, char ** argv)
> int fd;
> void *kernel;
> u32 crc = 0xffffffffUL;
> +#ifdef CONFIG_EFI_STUB
> + unsigned int init_sz;
> +#endif
>
> /* Defaults for old kernel */
> #ifdef CONFIG_X86_32
> @@ -343,7 +364,9 @@ int main(int argc, char ** argv)
> put_unaligned_le32(sys_size, &buf[0x1f4]);
>
> #ifdef CONFIG_EFI_STUB
> - update_pecoff_text(setup_sectors * 512, sz + i + ((sys_size * 16) - sz));
> + update_pecoff_text(setup_sectors * 512, i + (sys_size * 16));
> + init_sz = get_unaligned_le32(&buf[0x260]);
> + update_pecoff_bss(i + (sys_size * 16), init_sz);
>
> #ifdef CONFIG_X86_64 /* Yes, this is really how we defined it :( */
> efi_stub_entry -= 0x200;
> --
> 1.8.4.5
>
> --
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