From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2509930FF30; Mon, 13 Oct 2025 15:06:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760367984; cv=none; b=GMDt8TnLcd9ra8E8MXz+d4ne9tfVi5NM7iDNZ1xm2K+L9YNf+0NxSAtfpG9Vx4u9cTTUx2B50Y9ZUvFERVUW8nCbO3pnpQ5tZZ/dj3HVDriIII2ohdr6QPwtD/yibbgoF2l6zQDOHXjHnMZqmHOdfnoAeFuAW60BhnbnhhjHjzc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760367984; c=relaxed/simple; bh=pWOsfcWoSbqH0xUXdZtA5u9LR0QjGTcp1Tjsq0TzBoo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SjHUWTsBq18C4anFdRnT78sgY2963nh107IZo2Ck4IfKwESlc0oKLC6sZ+VAWzQPy3UZS35lXwCjsaRl0Kp+gt+voT18CLAmokW8910o8DzdALNuBOaWM+vBXuO1hCt1onse+LqSOhOMBVXttrnVuyPKYlnFF7H9oVG2NpksPL4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=v7keJjuP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="v7keJjuP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9CDDEC4CEFE; Mon, 13 Oct 2025 15:06:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1760367984; bh=pWOsfcWoSbqH0xUXdZtA5u9LR0QjGTcp1Tjsq0TzBoo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=v7keJjuPUsamNrZ7oSf6qFnfpa5jTNYRaY9i37ZogE82/AImY2In0zZjIjRxhejOt rW5e8ivdo+9MfyDZ+zvR6RAzr3WjJyhE0DxLhiUoqowCsjDMTHE1/2H9OEOCoEJ12M xirOfM1SoNKBDpUINXg7+fm6IOx72QShqj5vb/8s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zheng Qixing , Mikulas Patocka Subject: [PATCH 6.6 178/196] dm: fix NULL pointer dereference in __dm_suspend() Date: Mon, 13 Oct 2025 16:46:09 +0200 Message-ID: <20251013144321.748490995@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251013144315.184275491@linuxfoundation.org> References: <20251013144315.184275491@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zheng Qixing commit 8d33a030c566e1f105cd5bf27f37940b6367f3be upstream. There is a race condition between dm device suspend and table load that can lead to null pointer dereference. The issue occurs when suspend is invoked before table load completes: BUG: kernel NULL pointer dereference, address: 0000000000000054 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 6 PID: 6798 Comm: dmsetup Not tainted 6.6.0-g7e52f5f0ca9b #62 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:blk_mq_wait_quiesce_done+0x0/0x50 Call Trace: blk_mq_quiesce_queue+0x2c/0x50 dm_stop_queue+0xd/0x20 __dm_suspend+0x130/0x330 dm_suspend+0x11a/0x180 dev_suspend+0x27e/0x560 ctl_ioctl+0x4cf/0x850 dm_ctl_ioctl+0xd/0x20 vfs_ioctl+0x1d/0x50 __se_sys_ioctl+0x9b/0xc0 __x64_sys_ioctl+0x19/0x30 x64_sys_call+0x2c4a/0x4620 do_syscall_64+0x9e/0x1b0 The issue can be triggered as below: T1 T2 dm_suspend table_load __dm_suspend dm_setup_md_queue dm_mq_init_request_queue blk_mq_init_allocated_queue => q->mq_ops = set->ops; (1) dm_stop_queue / dm_wait_for_completion => q->tag_set NULL pointer! (2) => q->tag_set = set; (3) Fix this by checking if a valid table (map) exists before performing request-based suspend and waiting for target I/O. When map is NULL, skip these table-dependent suspend steps. Even when map is NULL, no I/O can reach any target because there is no table loaded; I/O submitted in this state will fail early in the DM layer. Skipping the table-dependent suspend logic in this case is safe and avoids NULL pointer dereferences. Fixes: c4576aed8d85 ("dm: fix request-based dm's use of dm_wait_for_completion") Cc: stable@vger.kernel.org Signed-off-by: Zheng Qixing Signed-off-by: Mikulas Patocka Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2688,7 +2688,7 @@ static int __dm_suspend(struct mapped_de { bool do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG; bool noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG; - int r; + int r = 0; lockdep_assert_held(&md->suspend_lock); @@ -2740,7 +2740,7 @@ static int __dm_suspend(struct mapped_de * Stop md->queue before flushing md->wq in case request-based * dm defers requests to md->wq from md->queue. */ - if (dm_request_based(md)) { + if (map && dm_request_based(md)) { dm_stop_queue(md->queue); set_bit(DMF_QUEUE_STOPPED, &md->flags); } @@ -2752,7 +2752,8 @@ static int __dm_suspend(struct mapped_de * We call dm_wait_for_completion to wait for all existing requests * to finish. */ - r = dm_wait_for_completion(md, task_state); + if (map) + r = dm_wait_for_completion(md, task_state); if (!r) set_bit(dmf_suspended_flag, &md->flags);