From: Chris Malley <mail@chrismalley.co.uk>
Date: Wed, 26 Sep 2007 04:19:18 +0000 (+1000)
Subject: lguest example launcher truncates block device file to 0 length on problems
X-Git-Tag: firefly_0821_release~26415
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f6a592e8abd2f2394623ce5427cbb4c265495974;p=firefly-linux-kernel-4.4.55.git

lguest example launcher truncates block device file to 0 length on problems

The function should also use ftruncate64() rather than ftruncate() to prevent
files over 4GB (not uncommon for a root filesystem) being zeroed.

Signed-off-by: Chris Malley <mail@chrismalley.co.uk>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index f7918401a007..73c5f1f3d5d2 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -882,7 +882,7 @@ static u32 handle_block_output(int fd, const struct iovec *iov,
 		 * of the block file (possibly extending it). */
 		if (off + len > device_len) {
 			/* Trim it back to the correct length */
-			ftruncate(dev->fd, device_len);
+			ftruncate64(dev->fd, device_len);
 			/* Die, bad Guest, die. */
 			errx(1, "Write past end %llu+%u", off, len);
 		}