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x86/efi: Include a .bss section within the PE/COFF headers
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@fensystems.co.uk> Cc: Thomas Bächler <thomas@archlinux.org> Cc: Josh Boyer <jwboyer@fedoraproject.org> Cc: <stable@vger.kernel.org> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
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@ -91,10 +91,9 @@ bs_die:
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.section ".bsdata", "a"
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bugger_off_msg:
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.ascii "Direct floppy boot is not supported. "
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.ascii "Use a boot loader program instead.\r\n"
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.ascii "Use a boot loader.\r\n"
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.ascii "\n"
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.ascii "Remove disk and press any key to reboot ...\r\n"
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.ascii "Remove disk and press any key to reboot...\r\n"
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.byte 0
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#ifdef CONFIG_EFI_STUB
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@ -108,7 +107,7 @@ coff_header:
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#else
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.word 0x8664 # x86-64
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#endif
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.word 3 # nr_sections
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.word 4 # nr_sections
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.long 0 # TimeDateStamp
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.long 0 # PointerToSymbolTable
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.long 1 # NumberOfSymbols
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@ -250,6 +249,25 @@ section_table:
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.word 0 # NumberOfLineNumbers
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.long 0x60500020 # Characteristics (section flags)
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#
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# The offset & size fields are filled in by build.c.
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#
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.ascii ".bss"
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.byte 0
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.byte 0
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.byte 0
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.byte 0
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.long 0
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.long 0x0
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.long 0 # Size of initialized data
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# on disk
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.long 0x0
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.long 0 # PointerToRelocations
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.long 0 # PointerToLineNumbers
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.word 0 # NumberOfRelocations
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.word 0 # NumberOfLineNumbers
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.long 0xc8000080 # Characteristics (section flags)
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#endif /* CONFIG_EFI_STUB */
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# Kernel attributes; used by setup. This is part 1 of the
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@ -143,7 +143,7 @@ static void usage(void)
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#ifdef CONFIG_EFI_STUB
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static void update_pecoff_section_header(char *section_name, u32 offset, u32 size)
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static void update_pecoff_section_header_fields(char *section_name, u32 vma, u32 size, u32 datasz, u32 offset)
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{
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unsigned int pe_header;
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unsigned short num_sections;
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@ -164,10 +164,10 @@ static void update_pecoff_section_header(char *section_name, u32 offset, u32 siz
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put_unaligned_le32(size, section + 0x8);
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/* section header vma field */
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put_unaligned_le32(offset, section + 0xc);
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put_unaligned_le32(vma, section + 0xc);
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/* section header 'size of initialised data' field */
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put_unaligned_le32(size, section + 0x10);
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put_unaligned_le32(datasz, section + 0x10);
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/* section header 'file offset' field */
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put_unaligned_le32(offset, section + 0x14);
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@ -179,6 +179,11 @@ static void update_pecoff_section_header(char *section_name, u32 offset, u32 siz
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}
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}
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static void update_pecoff_section_header(char *section_name, u32 offset, u32 size)
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{
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update_pecoff_section_header_fields(section_name, offset, size, size, offset);
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}
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static void update_pecoff_setup_and_reloc(unsigned int size)
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{
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u32 setup_offset = 0x200;
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@ -203,9 +208,6 @@ static void update_pecoff_text(unsigned int text_start, unsigned int file_sz)
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pe_header = get_unaligned_le32(&buf[0x3c]);
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/* Size of image */
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put_unaligned_le32(file_sz, &buf[pe_header + 0x50]);
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/*
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* Size of code: Subtract the size of the first sector (512 bytes)
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* which includes the header.
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@ -220,6 +222,22 @@ static void update_pecoff_text(unsigned int text_start, unsigned int file_sz)
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update_pecoff_section_header(".text", text_start, text_sz);
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}
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static void update_pecoff_bss(unsigned int file_sz, unsigned int init_sz)
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{
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unsigned int pe_header;
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unsigned int bss_sz = init_sz - file_sz;
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pe_header = get_unaligned_le32(&buf[0x3c]);
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/* Size of uninitialized data */
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put_unaligned_le32(bss_sz, &buf[pe_header + 0x24]);
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/* Size of image */
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put_unaligned_le32(init_sz, &buf[pe_header + 0x50]);
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update_pecoff_section_header_fields(".bss", file_sz, bss_sz, 0, 0);
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}
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static int reserve_pecoff_reloc_section(int c)
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{
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/* Reserve 0x20 bytes for .reloc section */
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@ -259,6 +277,8 @@ static void efi_stub_entry_update(void)
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static inline void update_pecoff_setup_and_reloc(unsigned int size) {}
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static inline void update_pecoff_text(unsigned int text_start,
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unsigned int file_sz) {}
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static inline void update_pecoff_bss(unsigned int file_sz,
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unsigned int init_sz) {}
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static inline void efi_stub_defaults(void) {}
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static inline void efi_stub_entry_update(void) {}
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@ -310,7 +330,7 @@ static void parse_zoffset(char *fname)
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int main(int argc, char ** argv)
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{
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unsigned int i, sz, setup_sectors;
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unsigned int i, sz, setup_sectors, init_sz;
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int c;
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u32 sys_size;
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struct stat sb;
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@ -376,7 +396,9 @@ int main(int argc, char ** argv)
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buf[0x1f1] = setup_sectors-1;
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put_unaligned_le32(sys_size, &buf[0x1f4]);
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update_pecoff_text(setup_sectors * 512, sz + i + ((sys_size * 16) - sz));
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update_pecoff_text(setup_sectors * 512, i + (sys_size * 16));
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init_sz = get_unaligned_le32(&buf[0x260]);
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update_pecoff_bss(i + (sys_size * 16), init_sz);
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efi_stub_entry_update();
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