commands: md: don't leak heap memory with unaligned accesses

Doing unaligned near file end returns bogus results:

	barebox@Sandbox:/ md -s /dev/stickypage 4095
	00000fff: 959ff8ff                                           .

That 0x959ff8 is heap memory next to the buffer md had allocated.
Fix this by adding some zeroed padding after the buffer, so it instead
reads:

	00000fff: 000000ff                                           .

This is arguably better user experience.
This only applies to non-mappable fd's. For e.g. /dev/mem, unaligned
accesses will still be passed as-is.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Link: https://lore.barebox.org/20210619054217.499815-1-ahmad@a3f.at
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/commands/md.c b/commands/md.c
index ef6a1e1bc0..d80c7cca0c 100644
--- a/commands/md.c
+++ b/commands/md.c
@@ -59,7 +59,7 @@ static int do_mem_md(int argc, char *argv[])
 		goto out;
 	}
 
-	buf = xmalloc(RW_BUF_SIZE);
+	buf = xzalloc(RW_BUF_SIZE + 7);
 
 	do {
 		now = min(size, (loff_t)RW_BUF_SIZE);