From 82497fa02d60757c2cfa645cf89a79abb1435273 Mon Sep 17 00:00:00 2001

From: Jean Delvare <jdelvare@suse.de>

Date: Fri, 16 Nov 2018 11:18:25 +0100

Subject: [PATCH 02/18] dmidecode: Don't use memcpy on /dev/mem on arm64

On arm64, calling memcpy on /dev/mem will cause a bus error if the

start and the end of the buffer are not aligned on a 64-bit boundary.

Using option --no-sysfs triggers this.

Use a slow manual byte-by-byte copy in that case, to prevent the bus

error. This is only a fallback path (at least on Linux) and not

performance-critical anyway, as it is a one-time operation and DMI

tables are usually not too large.

This fixes bug #55026:

https://savannah.nongnu.org/bugs/index.php?55026

Signed-off-by: Jean Delvare <jdelvare@suse.de>

---

 config.h |  5 +++++

 util.c   | 14 +++++++++++++-

 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/config.h b/config.h

index e39091f..4237355 100644

--- a/config.h

+++ b/config.h

@@ -26,4 +26,9 @@

 #define ALIGNMENT_WORKAROUND

 #endif

+/* Avoid unaligned memcpy on /dev/mem */

+#ifdef __aarch64__

+#define USE_SLOW_MEMCPY

+#endif

+

 #endif

diff --git a/util.c b/util.c

index eeffdae..04aaadd 100644

--- a/util.c

+++ b/util.c

@@ -155,6 +155,18 @@ void *read_file(off_t base, size_t *max_len, const char *filename)

 	return p;

 }

+static void safe_memcpy(void *dest, const void *src, size_t n)

+{

+#ifdef USE_SLOW_MEMCPY

+	size_t i;

+

+	for (i = 0; i < n; i++)

+		*((u8 *)dest + i) = *((const u8 *)src + i);

+#else

+	memcpy(dest, src, n);

+#endif

+}

+

 /*

  * Copy a physical memory chunk into a memory buffer.

  * This function allocates memory.

@@ -214,7 +226,7 @@ void *mem_chunk(off_t base, size_t len, const char *devmem)

 	if (mmp == MAP_FAILED)

 		goto try_read;

-	memcpy(p, (u8 *)mmp + mmoffset, len);

+	safe_memcpy(p, (u8 *)mmp + mmoffset, len);

 	if (munmap(mmp, mmoffset + len) == -1)

 	{

-- 

2.24.0