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From: Sascha Hauer <s.hauer@pengutronix.de>
To: Barebox List <barebox@lists.infradead.org>
Subject: [PATCH 3/4] fs: Fix use after free
Date: Mon, 14 Sep 2020 15:06:39 +0200	[thread overview]
Message-ID: <20200914130640.21416-3-s.hauer@pengutronix.de> (raw)
In-Reply-To: <20200914130640.21416-1-s.hauer@pengutronix.de>

In case of the fs mounted to '/' the root dentry of the mounted
filesystem is the place where it's mounted itself, so sb->s_root
is the same as fsdev->vfsmount.mountpoint. In that case make
sure we only access it before it has been killed in
dentry_delete_subtree().

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 fs/fs.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/fs.c b/fs/fs.c
index a6c6f0cc93..5784e9c1f3 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -667,14 +667,14 @@ static void fs_remove(struct device_d *dev)
 	if (fsdev->loop && fsdev->cdev)
 		cdev_remove_loop(fsdev->cdev);
 
+	if (fsdev->vfsmount.mountpoint)
+		fsdev->vfsmount.mountpoint->d_flags &= ~DCACHE_MOUNTED;
+
 	dentry_delete_subtree(sb, sb->s_root);
 
 	list_for_each_entry_safe(inode, tmp, &sb->s_inodes, i_sb_list)
 		destroy_inode(inode);
 
-	if (fsdev->vfsmount.mountpoint)
-		fsdev->vfsmount.mountpoint->d_flags &= ~DCACHE_MOUNTED;
-
 	mntput(fsdev->vfsmount.parent);
 
 	free(fsdev->backingstore);
-- 
2.28.0


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  parent reply	other threads:[~2020-09-14 13:06 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-14 13:06 [PATCH 1/4] fs: don't free device in remove callback Sascha Hauer
2020-09-14 13:06 ` [PATCH 2/4] fs: Drop unnecessary dput() Sascha Hauer
2020-09-14 13:06 ` Sascha Hauer [this message]
2020-09-14 13:06 ` [PATCH 4/4] fs: free unused dentries Sascha Hauer
2020-09-15  5:25   ` Ahmad Fatoum
2020-09-15  7:12     ` Sascha Hauer
2020-09-15  8:01       ` Ahmad Fatoum
2020-09-15 13:12         ` Sascha Hauer
2020-09-15 13:28           ` Ahmad Fatoum
2020-09-16 10:43             ` Ahmad Fatoum

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