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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
--
2.6.4
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