From 364055211b1956539c6a6268e111e244e1292c8c Mon Sep 17 00:00:00 2001

From: Jean Delvare <jdelvare@suse.de>

Date: Mon, 2 Nov 2015 09:45:31 +0100

Subject: [PATCH 8/9] dmidecode: Use read_file() to read the DMI table from

 sysfs

We shouldn't use mem_chunk() to read the DMI table from sysfs. This

will fail for SMBIOS v3 implementations which specify a maximum length

for the table rather than its exact length. The kernel will trim the

table to the actual length, so the DMI file will be shorter than the

length announced in entry point.

read_file() fits the bill in this case, as it deals with end of file

nicely.

This also helps with corrupted DMI tables, as the kernel will not

export the part of the table that it wasn't able to parse, effectively

trimming it.

This fixes bug #46176:

https://savannah.nongnu.org/bugs/?46176

Unexpected end of file error

---

 CHANGELOG   |  3 +++

 dmidecode.c | 29 +++++++++++++++++++++--------

 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG

index 1e5437a..fcfc244 100644

--- a/CHANGELOG

+++ b/CHANGELOG

@@ -2,6 +2,9 @@

 	* dmidecode.c, util.c, util.h: Let read_file return the actual data

 	  size.

+	* dmidecode.c: Use read_file to read the DMI table from sysfs.

+	  This fixes Savannah bug #46176:

+	  https://savannah.nongnu.org/bugs/?46176

 2015-10-21  Xie XiuQi  <xiexiuqi@huawei.com>

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

index a43cfd1..16d1823 100644

--- a/dmidecode.c

+++ b/dmidecode.c

@@ -4524,16 +4524,29 @@ static void dmi_table(off_t base, u32 len, u16 num, u16 ver, const char *devmem,

 		printf("\n");

 	}

-	/*

-	 * When we are reading the DMI table from sysfs, we want to print

-	 * the address of the table (done above), but the offset of the

-	 * data in the file is 0.  When reading from /dev/mem, the offset

-	 * in the file is the address.

-	 */

 	if (flags & FLAG_NO_FILE_OFFSET)

-		base = 0;

+	{

+		/*

+		 * When reading from sysfs, the file may be shorter than

+		 * announced. For SMBIOS v3 this is expcted, as we only know

+		 * the maximum table size, not the actual table size. For older

+		 * implementations (and for SMBIOS v3 too), this would be the

+		 * result of the kernel truncating the table on parse error.

+		 */

+		size_t size = len;

+		buf = read_file(&size, devmem);

+		if (!(opt.flags & FLAG_QUIET) && num && size != (size_t)len)

+		{

+			printf("Wrong DMI structures length: %u bytes "

+				"announced, only %lu bytes available.\n",

+				len, (unsigned long)size);

+		}

+		len = size;

+	}

+	else

+		buf = mem_chunk(base, len, devmem);

-	if ((buf = mem_chunk(base, len, devmem)) == NULL)

+	if (buf == NULL)

 	{

 		fprintf(stderr, "Table is unreachable, sorry."

 #ifndef USE_MMAP

-- 

2.5.0