Description: 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.
Author: Jean Delvare <jdelvare@suse.de>
Origin: https://savannah.nongnu.org/bugs/download.php?file_id=35008
Bug: https://savannah.nongnu.org/bugs/index.php?46066
Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=796963
Last-Update: 2015-10-01
----
This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
--- dmidecode.orig/util.c	2015-09-29 11:27:02.136566009 +0200
+++ dmidecode/util.c	2015-09-29 11:37:24.746191083 +0200
@@ -152,6 +152,7 @@ void *mem_chunk(off_t base, size_t len,
 	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,
 	}
 
 #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