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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
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