mmap()->sys_mmap2: do unsigned shift of offset

Fix the implementation of mmap based on the mmap2 system call, to
construct pgoffset from offset with an unsigned shift rather than a
signed (off_t) shift. The mmap2 test in the testsuite catches this case
by mmap'ing with a large offset (with the sign bit set). The signed
shift repeats the sign bit making the page shift way out of range. This
is already fixed similarly in mmap64().

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

libc/sysdeps/linux/common/mmap.c

@@ -63,7 +63,8 @@ __ptr_t mmap(__ptr_t addr, size_t len, int prot, int flags, int fd, __off_t offs
 		__set_errno(EINVAL);
 		return MAP_FAILED;
 	}
-	return __syscall_mmap2(addr, len, prot, flags, fd, offset >> MMAP2_PAGE_SHIFT);
+	return __syscall_mmap2(addr, len, prot, flags,
+	                       fd, ((__u_long) offset >> MMAP2_PAGE_SHIFT));
 }
 
 libc_hidden_def(mmap)