commit c7fb93ec51d462ec3540a729ba446663c26a0505 upstream
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
--
To unsubscribe from this list: send the line "unsubscribe linux-efi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
