126 lines
4.1 KiB
Diff
126 lines
4.1 KiB
Diff
From: Matt Fleming <matt.fleming@intel.com>
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Date: Tue, 28 Feb 2012 13:37:24 +0000
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Subject: [PATCH 15/17] x86, efi: Fix endian issues and unaligned accesses
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commit 92f42c50f227ad228f815a8f4eec872524dae3a5 upstream.
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We may need to convert the endianness of the data we read from/write
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to 'buf', so let's use {get,put}_unaligned_le32() to do that. Failure
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to do so can result in accessing invalid memory, leading to a
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segfault. Stephen Rothwell noticed this bug while cross-building an
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x86_64 allmodconfig kernel on PowerPC.
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We need to read from and write to 'buf' a byte at a time otherwise
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it's possible we'll perform an unaligned access, which can lead to bus
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errors when cross-building an x86 kernel on risc architectures.
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Cc: H. Peter Anvin <hpa@zytor.com>
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Cc: Nick Bowler <nbowler@elliptictech.com>
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Tested-by: Stephen Rothwell <sfr@canb.auug.org.au>
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Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
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Signed-off-by: Matt Fleming <matt.fleming@intel.com>
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Link: http://lkml.kernel.org/r/1330436245-24875-6-git-send-email-matt@console-pimps.org
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Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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---
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arch/x86/boot/tools/build.c | 31 +++++++++++++++----------------
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1 file changed, 15 insertions(+), 16 deletions(-)
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diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
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index 4e9bd6b..f2ac95e 100644
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--- a/arch/x86/boot/tools/build.c
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+++ b/arch/x86/boot/tools/build.c
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@@ -34,6 +34,7 @@
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <asm/boot.h>
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+#include <tools/le_byteshift.h>
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typedef unsigned char u8;
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typedef unsigned short u16;
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@@ -41,6 +42,7 @@ typedef unsigned long u32;
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#define DEFAULT_MAJOR_ROOT 0
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#define DEFAULT_MINOR_ROOT 0
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+#define DEFAULT_ROOT_DEV (DEFAULT_MAJOR_ROOT << 8 | DEFAULT_MINOR_ROOT)
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/* Minimal number of setup sectors */
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#define SETUP_SECT_MIN 5
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@@ -159,7 +161,7 @@ int main(int argc, char ** argv)
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die("read-error on `setup'");
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if (c < 1024)
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die("The setup must be at least 1024 bytes");
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- if (buf[510] != 0x55 || buf[511] != 0xaa)
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+ if (get_unaligned_le16(&buf[510]) != 0xAA55)
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die("Boot block hasn't got boot flag (0xAA55)");
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fclose(file);
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@@ -171,8 +173,7 @@ int main(int argc, char ** argv)
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memset(buf+c, 0, i-c);
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/* Set the default root device */
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- buf[508] = DEFAULT_MINOR_ROOT;
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- buf[509] = DEFAULT_MAJOR_ROOT;
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+ put_unaligned_le16(DEFAULT_ROOT_DEV, &buf[508]);
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fprintf(stderr, "Setup is %d bytes (padded to %d bytes).\n", c, i);
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@@ -192,44 +193,42 @@ int main(int argc, char ** argv)
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/* Patch the setup code with the appropriate size parameters */
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buf[0x1f1] = setup_sectors-1;
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- buf[0x1f4] = sys_size;
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- buf[0x1f5] = sys_size >> 8;
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- buf[0x1f6] = sys_size >> 16;
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- buf[0x1f7] = sys_size >> 24;
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+ put_unaligned_le32(sys_size, &buf[0x1f4]);
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#ifdef CONFIG_EFI_STUB
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file_sz = sz + i + ((sys_size * 16) - sz);
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- pe_header = *(unsigned int *)&buf[0x3c];
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+ pe_header = get_unaligned_le32(&buf[0x3c]);
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/* Size of code */
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- *(unsigned int *)&buf[pe_header + 0x1c] = file_sz;
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+ put_unaligned_le32(file_sz, &buf[pe_header + 0x1c]);
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/* Size of image */
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- *(unsigned int *)&buf[pe_header + 0x50] = file_sz;
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+ put_unaligned_le32(file_sz, &buf[pe_header + 0x50]);
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#ifdef CONFIG_X86_32
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/* Address of entry point */
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- *(unsigned int *)&buf[pe_header + 0x28] = i;
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+ put_unaligned_le32(i, &buf[pe_header + 0x28]);
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/* .text size */
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- *(unsigned int *)&buf[pe_header + 0xb0] = file_sz;
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+ put_unaligned_le32(file_sz, &buf[pe_header + 0xb0]);
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/* .text size of initialised data */
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- *(unsigned int *)&buf[pe_header + 0xb8] = file_sz;
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+ put_unaligned_le32(file_sz, &buf[pe_header + 0xb8]);
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#else
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/*
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* Address of entry point. startup_32 is at the beginning and
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* the 64-bit entry point (startup_64) is always 512 bytes
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* after.
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*/
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- *(unsigned int *)&buf[pe_header + 0x28] = i + 512;
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+ put_unaligned_le32(i + 512, &buf[pe_header + 0x28]);
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/* .text size */
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- *(unsigned int *)&buf[pe_header + 0xc0] = file_sz;
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+ put_unaligned_le32(file_sz, &buf[pe_header + 0xc0]);
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/* .text size of initialised data */
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- *(unsigned int *)&buf[pe_header + 0xc8] = file_sz;
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+ put_unaligned_le32(file_sz, &buf[pe_header + 0xc8]);
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+
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#endif /* CONFIG_X86_32 */
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#endif /* CONFIG_EFI_STUB */
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--
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1.7.10
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