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vfs: avoid hang caused by attempting to rmdir an invalid file system

Message ID 1338226445-8911-1-git-send-email-tytso@mit.edu
State Not Applicable, archived
Headers show

Commit Message

Theodore Ts'o May 28, 2012, 5:34 p.m. UTC 
If we rmdir a directory which is a hard link to '.', we will deadlock
trying to grab the directory's i_mutex.  Check for this condition and
return EINVAL, which is what we return if the user attempts to rmdir
"/foo/bar/."

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 fs/namei.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
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Patch

diff --git a/fs/namei.c b/fs/namei.c
index 0062dd1..081f872 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2774,6 +2774,17 @@  static long do_rmdir(int dfd, const char __user *pathname)
 		error = -ENOENT;
 		goto exit3;
 	}
+	if (nd.path.dentry->d_inode == dentry->d_inode) {
+		/*
+		 * Corrupt file system where there is a symlink to
+		 * '.'; treat it as if we are trying to rmdir '.'
+		 *
+		 * XXX Should we call into the low-level file system
+		 * to request that the file system be marked corrupt?
+		 */
+		error = -EINVAL;
+		goto exit3;
+	}
 	error = mnt_want_write(nd.path.mnt);
 	if (error)
 		goto exit3;