From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794061747; b=SJBCLZUpWXI535AnD/kopmxwfG0slcAxmiexO2g9zbhDQK8BrvsreytwuvGk9jrcSGNm bWwB/pPSakTS6XBwsDnRROz8OxtvwR44AhumRKkYjOggcaEYYRKW6xOhMOpDFQ2H8lKkE Z1FuvKgZxc+26iPGiFrh10rAr8TfkmTHFlB/Y1TuPfPvw7x5YkYpJaLp2p5eC2fZyyS49 kasNhhibc8VfV//yvSbVKgZIduM7sqkEyFk9C2sj6w8HSyoNSFga3013quYtOpTu+ZZZa L/EufLeHgHBtrGfFnNezAI46CZdDEcy+Mkg/vKkZpCI9EsWYk6VSJyU3DHzn6i9Nk+Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794061747; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=ZYV51SrBFsNZEzf9HGqhN+wO9kyHJ973pK6Vc/tQ3dY=; b=jgtPZU3vLJwOxwi4L/Rrdq0e5d0LJMj54zbk8/UkNkKMt/4fQjls47SRwvjNOvW01FSy HeDXBTN+F8m7hcalzNN3iDDSRf1a22cinNDVeweojoeY+3P/KEQl08v4Ha1v05wfEDG2j sbTIgRgLqH4HPYvd0prJnA3AZaGxq6rQ0YZbxcHMuuqWgf3EallbqcGj6Gtd1bF4OXiD7 qQ0RyaIbZN3k9MtQ6lqpim3RBpR78BqZ6wP16VJKEcFpO6cVZs7R0m1AWl6eXcL/aoL1S 5Gyj8ugLRNXuPU5S8uoRXAGo2nf9R18guuYeWAoQ269XjqsLcDDFXA5Rxp8SjQFBnDA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=LwYuJjUy; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E7BA0606A326; Sat, 7 Nov 2026 14:29:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=LwYuJjUy Received: by smtp.kernel.org (Postfix) with ESMTPSA id 999E01F0089F; Sat, 7 Nov 2026 14:29:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794061746; bh=ZYV51SrBFsNZEzf9HGqhN+wO9kyHJ973pK6Vc/tQ3dY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LwYuJjUyaPjO7R3U4F+mmBY5azsP+HZV7pzv9thbpbTNfnIsQ0lflYzUAoeq+bWJQ FSnlKelcR/MjjJy4eIvKB4ye3wjRXkgfjqs2fXrhHGeD/pLgqwxSyIVxRbqmoA9cyv WauoGFHU+kD3Eko32a36St9eK1ri1Y92M9edCcuM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Namjae Jeon , Paulo Alcantara , David Howells , Ronnie Sahlberg , Shyam Prasad N , Tom Talpey , Bharath SM Subject: [PATCH 6.12 0748/1536] smb: client: dont resurrect an exiting tcon from cached dir workers Date: Sat, 7 Nov 2026 08:46:04 -0500 Message-ID: <20261107135018.540293618@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paulo Alcantara commit d58e7b40908a8a57755811d5b37af1df3380278f upstream. cfids_laundromat_worker() bumps tcon->tc_count for every expired open cfid and queues cached_dir_offload_close() without checking whether the tcon is already being torn down. Racing with the final cifs_put_tcon(), the tcon comes back from zero and gets torn down twice: T1 T2 cifs_put_tcon() --tc_count == 0, TID_EXITING tconInfoFree() free_cached_dirs() cancel_delayed_work_sync() cfids_laundromat_worker() ++tc_count == 1 queue_work(serverclose_wq) kfree(tcon->origin_fullpath) kfree(tcon) cached_dir_offload_close() close_cached_dir() [UAF] cifs_put_tcon() tconInfoFree() [double free] cached_dir_lease_break() also bumps tc_count without tc_lock, racing with the laundromat's locked update. Take the tcon reference through a helper that refuses once the tcon is TID_EXITING or its refcount has dropped to zero. Queued put_work and close_work then always hold a tcon reference, so tconInfoFree() can't run before they finish and free_cached_dirs() doesn't need to flush any workqueue. If the laundromat can't get a reference, put the cfid back on the dying list for free_cached_dirs() to free; its handle goes away with the tree connection. The lease break path finds the tcon on ses->tcon_list under cifs_tcp_ses_lock, so it can't see TID_EXITING, but it now takes tc_lock. Fixes: 3fa640d035e5 ("smb: During unmount, ensure all cached dir instances drop their dentry") Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: David Howells Cc: Namjae Jeon Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/cached_dir.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) --- a/fs/smb/client/cached_dir.c +++ b/fs/smb/client/cached_dir.c @@ -614,6 +614,17 @@ void invalidate_all_cached_dirs(struct c spin_unlock(&cfids->cfid_list_lock); } +static bool cached_dir_get_tcon(struct cifs_tcon *tcon, + enum smb3_tcon_ref_trace trace) +{ + guard(spinlock)(&tcon->tc_lock); + if (tcon->status == TID_EXITING || tcon->tc_count <= 0) + return false; + ++tcon->tc_count; + trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count, trace); + return true; +} + static void cached_dir_offload_close(struct work_struct *work) { @@ -663,6 +674,9 @@ int cached_dir_lease_break(struct cifs_t !memcmp(lease_key, cfid->fid.lease_key, SMB2_LEASE_KEY_SIZE)) { + if (!cached_dir_get_tcon(tcon, + netfs_trace_tcon_ref_get_cached_lease_break)) + break; cfid->has_lease = false; cfid->time = 0; /* @@ -673,9 +687,6 @@ int cached_dir_lease_break(struct cifs_t cfid->on_list = false; cfids->num_entries--; - ++tcon->tc_count; - trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count, - netfs_trace_tcon_ref_get_cached_lease_break); queue_work(cfid_put_wq, &cfid->put_work); spin_unlock(&cfids->cfid_list_lock); return true; @@ -789,12 +800,13 @@ static void cfids_laundromat_worker(stru dput(dentry); if (cfid->is_open) { - spin_lock(&cfid->tcon->tc_lock); - ++cfid->tcon->tc_count; - trace_smb3_tcon_ref(cfid->tcon->debug_id, cfid->tcon->tc_count, - netfs_trace_tcon_ref_get_cached_laundromat); - spin_unlock(&cfid->tcon->tc_lock); - queue_work(serverclose_wq, &cfid->close_work); + if (cached_dir_get_tcon(cfid->tcon, + netfs_trace_tcon_ref_get_cached_laundromat)) { + queue_work(serverclose_wq, &cfid->close_work); + continue; + } + scoped_guard(spinlock, &cfids->cfid_list_lock) + list_add_tail(&cfid->entry, &cfids->dying); } else /* * Drop the ref-count from above, either the lease-ref (if there