1 files changed, 6 insertions, 0 deletions
diff --git a/compat/mmap.c b/compat/mmap.c
index 55cb120764..a4d2e507f7 100644
--- a/compat/mmap.c
+++ b/compat/mmap.c
@@ -7,6 +7,7 @@
 void *gitfakemmap(void *start, size_t length, int prot , int flags, int fd, off_t offset)
 {
 	int n = 0;
+	off_t current_offset = lseek(fd, 0, SEEK_CUR);
 
 	if (start != NULL || !(flags & MAP_PRIVATE))
 		die("Invalid usage of gitfakemmap.");
@@ -39,6 +40,11 @@ void *gitfakemmap(void *start, size_t length, int prot , int flags, int fd, off_
 		n += count;
 	}
 
+	if (current_offset != lseek(fd, current_offset, SEEK_SET)) {
+		errno = EINVAL;
+		return MAP_FAILED;
+	}
+
 	return start;
 }