From c081fa410e7c466df4b3b257e7b974b71fb7f250 Mon Sep 17 00:00:00 2001

From: Jean Delvare <jdelvare@suse.de>

Date: Wed, 14 Oct 2015 14:37:04 +0200

Subject: [PATCH 2/9] Avoid SIGBUS on mmap failure

mmap will fail with SIGBUS if trying to map a non-existent portion of

a file. While this should never happen with /dev/mem, it can happen if

passing a regular file with option -d. While people should no longer

do that, failure gracefully seems better than crashing. So check for

the file size before calling mmap.

This closes bug #46066:

http://savannah.nongnu.org/bugs/?46066

---

 CHANGELOG |  6 ++++++

 util.c    | 21 +++++++++++++++++++++

 2 files changed, 27 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG

index 42d815c..aa1c28f 100644

--- a/CHANGELOG

+++ b/CHANGELOG

@@ -1,3 +1,9 @@

+2015-10-14  Jean Delvare  <jdelvare@suse.de>

+

+	* util.c: Avoid SIGBUS on mmap failure.

+	  This fixes Savannah bug #46066:

+	  https://savannah.nongnu.org/bugs/?46066

+

 2015-10-01  Roy Franz  <roy.franz@linaro.org>

 	* dmiopt.c: Add "--no-sysfs" option description to -h output.

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

index 8cafe5c..5795d02 100644

--- a/util.c

+++ b/util.c

@@ -152,6 +152,7 @@ void *mem_chunk(off_t base, size_t len, const char *devmem)

 	void *p;

 	int fd;

 #ifdef USE_MMAP

+	struct stat statbuf;

 	off_t mmoffset;

 	void *mmp;

 #endif

@@ -169,6 +170,26 @@ void *mem_chunk(off_t base, size_t len, const char *devmem)

 	}

 #ifdef USE_MMAP

+	if (fstat(fd, &statbuf) == -1)

+	{

+		fprintf(stderr, "%s: ", devmem);

+		perror("stat");

+		free(p);

+		return NULL;

+	}

+

+	/*

+	 * mmap() will fail with SIGBUS if trying to map beyond the end of

+	 * the file.

+	 */

+	if (S_ISREG(statbuf.st_mode) && base + (off_t)len > statbuf.st_size)

+	{

+		fprintf(stderr, "mmap: Can't map beyond end of file %s\n",

+			devmem);

+		free(p);

+		return NULL;

+	}

+

 #ifdef _SC_PAGESIZE

 	mmoffset = base % sysconf(_SC_PAGESIZE);

 #else

-- 

2.5.0