From: Jan Kara <jack@suse.cz>
Date: Thu, 6 Aug 2009 22:27:27 +0000 (+0200)
Subject: udf: Fix possible corruption when close races with write
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=cbc8cc33529b0e0e55ae0ff077b8cb0b71d54c7a;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

udf: Fix possible corruption when close races with write

When we close a file, we remove preallocated blocks from it. But this
truncation was not protected by i_mutex and thus it could have raced with a
write through a different fd and cause crashes or even filesystem corruption.

Signed-off-by: Jan Kara <jack@suse.cz>
---

diff --git a/fs/udf/file.c b/fs/udf/file.c
index 7464305382b5..b80cbd78833c 100644
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -193,9 +193,11 @@ int udf_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
 static int udf_release_file(struct inode *inode, struct file *filp)
 {
 	if (filp->f_mode & FMODE_WRITE) {
+		mutex_lock(&inode->i_mutex);
 		lock_kernel();
 		udf_discard_prealloc(inode);
 		unlock_kernel();
+		mutex_unlock(&inode->i_mutex);
 	}
 	return 0;
 }