linux-ext4 - [PATCH] ext4: Prevent creation of files larger than RLIMIT

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Message-Id: <201005041115.04400.knikanth@suse.de>
Date:	Tue, 4 May 2010 11:15:04 +0530
From:	Nikanth Karthikesan <knikanth@...e.de>
To:	"Theodore Ts'o" <tytso@....edu>, Andreas Dilger <adilger@....com>,
	linux-ext4@...r.kernel.org
Cc:	"Amit K. Arora" <aarora@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>, coly.li@...e.de,
	Nick Piggin <npiggin@...e.de>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org,
	Eelis <opensuse.org@...tacts.eelis.net>,
	Amit Arora <aarora@...ibm.com>,
	Christoph Hellwig <hch@...radead.org>
Subject: [PATCH] ext4: Prevent creation of files larger than RLIMIT_FSIZE using fallocate

I assumed that Amit would send a patch with s-o-b, if not, please take
this patch.

Thanks
Nikanth

Prevent creation of files larger than RLIMIT_FSIZE using fallocate.

Currently using posix_fallocate one can bypass an RLIMIT_FSIZE limit
and create a file larger than the limit. Add a check for that.


Signed-off-by: Nikanth Karthikesan <knikanth@...e.de>

---

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 236b834..39b8123 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3672,6 +3672,11 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
 	 */
 	credits = ext4_chunk_trans_blocks(inode, max_blocks);
 	mutex_lock(&inode->i_mutex);
+	ret = inode_newsize_ok(inode, (len + offset));
+	if (ret) {
+		mutex_unlock(&inode->i_mutex);
+		return ret;
+	}
 retry:
 	while (ret >= 0 && ret < max_blocks) {
 		block = block + ret;
--
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