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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>
This commit is contained in:
Michael Brown 2014-07-10 12:26:20 +01:00 committed by Matt Fleming
parent 29e2435fd6
commit c7fb93ec51
2 changed files with 52 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
arch/x86/boot/header.S
View File

@ -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

38
arch/x86/boot/tools/build.c
View File

@ -143,7 +143,7 @@ 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;
@ -164,10 +164,10 @@ 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);
@ -179,6 +179,11 @@ 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;
@ -203,9 +208,6 @@ 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.
@ -220,6 +222,22 @@ 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);
}
static int reserve_pecoff_reloc_section(int c)
{
/* Reserve 0x20 bytes for .reloc section */
@ -259,6 +277,8 @@ static void efi_stub_entry_update(void)
static inline void update_pecoff_setup_and_reloc(unsigned int size) {}
static inline void update_pecoff_text(unsigned int text_start,
unsigned int file_sz) {}
static inline void update_pecoff_bss(unsigned int file_sz,
unsigned int init_sz) {}
static inline void efi_stub_defaults(void) {}
static inline void efi_stub_entry_update(void) {}
@ -310,7 +330,7 @@ static void parse_zoffset(char *fname)
int main(int argc, char ** argv)
{
unsigned int i, sz, setup_sectors;
unsigned int i, sz, setup_sectors, init_sz;
int c;
u32 sys_size;
struct stat sb;
@ -376,7 +396,9 @@ int main(int argc, char ** argv)
buf[0x1f1] = setup_sectors-1;
put_unaligned_le32(sys_size, &buf[0x1f4]);
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);
efi_stub_entry_update();