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=1793831524; b=5gpH/YXmKDSR4NSjk081oy3uZ6Zkh9URaI+CuQouSQaN4Yf/TXU/qEw1dlSC5WOQwgqC Xw/fYKfLpQbcosbpay4gwf9qIrw9r4x7f7FiXW3HvUbT3lwAIpCDcziDmuuluBBAPyXUY 4ddii0rfydhYX8AovaHwPutcWbSOF6Es4MTcQA/666Uv46pILWN0NBUwNwyuT8yj3YzsL hnq05sFmZhq/yXKzlTvmK5GjjvLQI6D6g/iZVLGAY0sqjJ/+oSspPDP7NYfS0gCBKFR2D vALyF9v8naJJw31p/cjGGFz67JGq33oUn4AN38TAFbDNNG7Hub6WHtauPPJ+PlSyNVA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831524; 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=5us5sz5ofU3wGXIGuBSwI71Kugr297Ky5GS1Uv/LYSs=; b=TRQ3JYmOKRpisWD7X+pC7UKAUnPd85w5QhJeBzxhP7EIOG9r1/h05MEPf5GpBsKBoLx5 DlXGPNCpOvifPpgQYA+aMNLMB6ECteT132VYWtDsNo34+BJPeOQrcUPQfOB7SGVxGMyqt DYP5KXr5xwWuDFEM7nvVr/UlpUVQCPW1F2oHaplfEjZ3A+Qy45o6ArAK6XK8uSsVe6Zct cTs4yH7HSoz8FytuKMejcZKfbkEhAsH52gShxMDX0Zt4cs7gXO723o71fyO20irh6aIMZ uznVpkfDV/Ab0iYrkFqLYqyiFdXyb0AAz7Q7AfuQkZ2MOkD81eX1YUqq3fFHPNaAKBA== 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=bI6C+MEW; 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 DC460606E806; Wed, 4 Nov 2026 22:32:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=bI6C+MEW Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6DA431F00919; Wed, 4 Nov 2026 22:32:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831523; bh=5us5sz5ofU3wGXIGuBSwI71Kugr297Ky5GS1Uv/LYSs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bI6C+MEWug91td5RP6st71+oBhyZ4oElG8+hUMBRhg6U8EyrEHFJ9ej7AwUObKn/2 HkwypwOzfyGubT2wOz5NctQG4ibrNyLzNpbU6tt8yTWPBt8/Dfp5Qts13eJqrZlzyq 0/1mnjBiTss+tgPnt3WLyYfiaYP3WPe9Nogtgu60= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Joseph Qi , Andrew Morton , Heming Zhao , Mark Fasheh , Joel Becker Subject: [PATCH 6.18 0754/1005] ocfs2/dlm: hold the lookup reference across convert AST enqueue Date: Wed, 4 Nov 2026 16:08:07 -0500 Message-ID: <20261104211104.565959140@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Joseph Qi commit 125fe08ff6cfa064e1212f586f01993ee45c0330 upstream. dlm_convert_lock_handler() drops the reference it took when it found the lock on res->granted at its leave label, one statement before it calls dlm_queue_ast(). dlm_free_dead_locks() takes res->spinlock and drops the list and base references, so a peer death landing in that gap leaves the handler's own put as the one that frees the lock, and __dlm_queue_ast() then reads lock->lockres from freed memory. The handler is registered next to dlm_create_lock_handler(), so a convert message buffered on a dying peer's socket arrives on the same o2net receive work that o2net_disconnect_node() does not wait for. The two can interleave as follows, with the reference counts as they are before this fix: Socket data-ready Node-down thread Receive worker ----------------- ---------------- -------------- o2net_data_ready() select sc under callback read lock o2net_disconnect_node() queue shutdown begin flush; new color queue sc_rx_work in the new color release callback lock shutdown socket flush returns read buffered convert_lock dlm_convert_lock_handler() find lock on res->granted dlm_lock_get() refs = 3 lock res->spinlock __dlmconvert_master() call_ast = 1 unlock res->spinlock DLM node-down cleanup lock res->spinlock dlm_free_dead_locks() unlink lock put list ref refs = 2 put base ref refs = 1 unlock res->spinlock dlm_lock_put() refs = 0 free lock dlm_queue_ast() __dlm_queue_ast() read lock->lockres (use-after-free) __dlmconvert_master() only moves the lock between lists, so the count entering the gap is base, list and lookup. Drop the lookup reference after the AST is queued instead of before it and the race ends with the one __dlm_queue_ast() took, which dlm_flush_asts() releases later with ast_pending cleared and ast_list unlinked. No extra get is needed, and the normal case ends with the same count as before. dlmconvert_master() has the same shape but is only reached from dlmlock() for a lock this node owns, which dlm_free_dead_locks() never matches. Link: https://lore.kernel.org/20261014112321.2955584-1-joseph.qi@linux.alibaba.com Fixes: 2c5c54aca9d0 ("ocfs2/dlm: Add missing dlm_lock_put()s") Signed-off-by: Joseph Qi Signed-off-by: Andrew Morton Reviewed-by: Heming Zhao Cc: Mark Fasheh Cc: Joel Becker Cc: Signed-off-by: Greg Kroah-Hartman --- fs/ocfs2/dlm/dlmconvert.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/fs/ocfs2/dlm/dlmconvert.c +++ b/fs/ocfs2/dlm/dlmconvert.c @@ -534,15 +534,19 @@ int dlm_convert_lock_handler(struct o2ne } leave: - if (lock) - dlm_lock_put(lock); - /* either queue the ast or release it, if reserved */ if (call_ast) dlm_queue_ast(dlm, lock); else if (ast_reserved) dlm_lockres_release_ast(dlm, res); + /* + * Keep the lock alive through AST enqueue: a concurrent + * dlm_free_dead_locks() drops the list and base references. + */ + if (lock) + dlm_lock_put(lock); + if (kick_thread) dlm_kick_thread(dlm, res);