linux-cifs.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Enzo Matsumiya <ematsumiya@suse.de>
To: linux-cifs@vger.kernel.org
Cc: pc@cjr.nz, Enzo Matsumiya <ematsumiya@suse.de>,
	Steve French <sfrench@samba.org>,
	samba-technical@lists.samba.org, linux-kernel@vger.kernel.org
Subject: [PATCH] cifs: properly invalidate cached root handle when closing it
Date: Thu,  9 Sep 2021 18:46:45 -0300	[thread overview]
Message-ID: <20210909214646.8790-1-ematsumiya@suse.de> (raw)

Cached root file was not being completely invalidated sometimes.

Reproducing:
- With a DFS share with 2 targets, one disabled and one enabled
- start some I/O on the mount
  # while true; do ls /mnt/dfs; done
- at the same time, disable the enabled target and enable the disabled
  one
- wait for DFS cache to expire
- on reconnect, the previous cached root handle should be invalid, but
  open_cached_dir_by_dentry() will still try to use it, but throws a
  use-after-free warning (kref_get())

Make smb2_close_cached_fid() invalidate all fields every time, but only
send an SMB2_close() when the entry is still valid.

Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/smb2ops.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 2dfd0d8297eb..1b9de38a136a 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -689,13 +689,19 @@ smb2_close_cached_fid(struct kref *ref)
 		cifs_dbg(FYI, "clear cached root file handle\n");
 		SMB2_close(0, cfid->tcon, cfid->fid->persistent_fid,
 			   cfid->fid->volatile_fid);
-		cfid->is_valid = false;
-		cfid->file_all_info_is_valid = false;
-		cfid->has_lease = false;
-		if (cfid->dentry) {
-			dput(cfid->dentry);
-			cfid->dentry = NULL;
-		}
+	}
+
+	/*
+	 * We only check validity above to send SMB2_close,
+	 * but we still need to invalidate these entries
+	 * when this function is called
+	 */
+	cfid->is_valid = false;
+	cfid->file_all_info_is_valid = false;
+	cfid->has_lease = false;
+	if (cfid->dentry) {
+		dput(cfid->dentry);
+		cfid->dentry = NULL;
 	}
 }
 
-- 
2.33.0


                 reply	other threads:[~2021-09-09 21:46 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210909214646.8790-1-ematsumiya@suse.de \
    --to=ematsumiya@suse.de \
    --cc=linux-cifs@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pc@cjr.nz \
    --cc=samba-technical@lists.samba.org \
    --cc=sfrench@samba.org \
    --subject='Re: [PATCH] cifs: properly invalidate cached root handle when closing it' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).