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From: Sascha Hauer <s.hauer@pengutronix.de>
To: Barebox List <barebox@lists.infradead.org>
Cc: Andrey Smirnov <andrew.smirnov@gmail.com>
Subject: [PATCH 3/5] fs: do not call truncate for FILE_SIZE_STREAM sized files
Date: Mon,  4 Feb 2019 15:46:39 +0100	[thread overview]
Message-ID: <20190204144641.19600-4-s.hauer@pengutronix.de> (raw)
In-Reply-To: <20190204144641.19600-1-s.hauer@pengutronix.de>

open_and_lseek() increases the file size when the file is opened in
write mode and scrolled past the files end. This fails badly on /dev/mem
because loff_t which we use for the file size is signed variable, which
is used as an unsigned variable in /dev/mem. To catch this case do not
try to truncate FILE_SIZE_STREAM sized files.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 fs/fs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/fs.c b/fs/fs.c
index c5b17e158a..1374286e62 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -213,6 +213,9 @@ int ftruncate(int fd, loff_t length)
 
 	f = &files[fd];
 
+	if (f->size == FILE_SIZE_STREAM)
+		return 0;
+
 	fsdrv = f->fsdev->driver;
 
 	ret = fsdrv->truncate(&f->fsdev->dev, f, length);
-- 
2.20.1


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  parent reply	other threads:[~2019-02-04 14:46 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-04 14:46 [PATCH 0/5] 32-bit lseek and /dev/mem fixes/improvements Sascha Hauer
2019-02-04 14:46 ` [PATCH 1/5] fs: let truncate take a loff_t argument Sascha Hauer
2019-02-04 14:46 ` [PATCH 2/5] fs: set errno in ftruncate() Sascha Hauer
2019-02-04 14:46 ` Sascha Hauer [this message]
2019-02-04 14:46 ` [PATCH 4/5] fs: devfs: forbid truncation when cdev has no truncate operation Sascha Hauer
2019-02-04 14:46 ` [PATCH 5/5] misc: fix /dev/mem size Sascha Hauer
2019-02-05 21:44 ` [PATCH 0/5] 32-bit lseek and /dev/mem fixes/improvements Andrey Smirnov
2019-02-06  7:33   ` Sascha Hauer
2019-02-06  7:37     ` Andrey Smirnov

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