From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 DAC69314B6D; Fri, 7 Aug 2026 15:22:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786116174; cv=none; b=APQeVk2wIrQ3zpuJstzcq11yaz0gEp+zfSh2g1XlLcbLuRC5OiM9eKl81xWI38g8YVMvZjakxcddn325TA/ATafkoaU/A+BLWR/2eH0XXa+WOhgsyiWOk77Ya+BFjuGKZGabjys4rrYdqUOtrVdUGZ1KTXyuVYjsH5MqNUyM6F0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786116174; c=relaxed/simple; bh=Ai6cfgCK0gC//W5Gm4zjAKpefqcDDppefsFloJ8CJfk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Zg1uPnOxfj3tCq6ee5ZZh2ooC7R2njvGNaNhQitPL76IrTOM7s2ONuuAn+ntnNgUUX/jewq6zRHKQ85lm90WWHKp9lk+u0qOzzIJL265MYeMhJpJmmX6GVBHSQDX7ZxyqLGEXG/HZtFD7QTO+LNPVmFfTV0CBzzxshhHIANRUlc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RzQMAFci; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RzQMAFci" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06BAA1F000E9; Fri, 7 Aug 2026 15:22:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786116172; bh=1ljTEAt41lDWE/8IWLQKn6fIrUE6F9m8Gx5KUdtnEjU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=RzQMAFciKYQMACMUZvJgg4aePJ6X2PpuSpGo05JphloEyg/WokDZS0iSBBShYgMWF rLRmzV+TKNiVumHwvzE2dtc1sw36AZeSl+aNjI33RIfxyMiR6ZWfPGo5ASuCpCz0hx OMb/WSFkCoYJYFLL6SbFz0U2HjxN5BTa//utWUBQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ming Lei , Caleb Sander Mateos , Jens Axboe Subject: [PATCH 6.6 138/261] ublk: reset kernel-owned dev_info fields in ublk_ctrl_add_dev() Date: Fri, 7 Aug 2026 16:38:15 +0200 Message-ID: <20260807143418.343056354@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260807143415.358597922@linuxfoundation.org> References: <20260807143415.358597922@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: Ming Lei commit e65848e4ce352bac9e3465099354c8b8f845391f upstream. ublk_ctrl_add_dev() memcpy()s the userspace ublksrv_ctrl_dev_info into ub->dev_info and then fixes up the fields the driver owns, but misses ->state and ->ublksrv_pid. A device added with ->state = UBLK_S_DEV_LIVE passes the "->state != UBLK_S_DEV_DEAD" test that ublk_stop_dev_unlocked() uses as its proxy for "a disk is attached", while ->ub_disk is still NULL, so DEL_DEV right after ADD_DEV oopses in del_gendisk(). UBLK_S_DEV_QUIESCED plus UBLK_F_USER_RECOVERY dies one step earlier, in ublk_force_abort_dev(). A poisoned ->state also gets START_USER_RECOVERY and the char device read/write path onto a device that was never started, and wedges START_DEV at -EEXIST. A poisoned ->ublksrv_pid just makes GET_DEV_INFO report an unrelated task as the ublk server. Reset both after the memcpy(), as ublk_detach_disk() does. Userspace only ever reads these back, so correcting them silently breaks nothing. ADD_DEV has copied ->state in unsanitized since ublk was merged, but back then it was harmless: the gendisk was allocated during ADD_DEV, and both teardown and the START_DEV -EEXIST check keyed off disk_live() rather than ->state. The oops became reachable once the disk allocation moved to START_DEV and those checks switched to ->state. Fixes: 6d9e6dfdf3b2 ("ublk: defer disk allocation") Cc: stable@vger.kernel.org Signed-off-by: Ming Lei Reviewed-by: Caleb Sander Mateos Link: https://patch.msgid.link/20260726145025.1507383-1-tom.leiming@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/block/ublk_drv.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -2438,6 +2438,15 @@ static int ublk_ctrl_add_dev(struct io_u ub->dev_info.dev_id = ub->ub_number; /* + * ->state and ->ublksrv_pid are owned by the driver and only read back + * by userspace, but they come from the copied-in dev_info, so reset + * them. Otherwise a device added with ->state != DEAD looks live while + * ->ub_disk is still NULL. + */ + ub->dev_info.state = UBLK_S_DEV_DEAD; + ub->dev_info.ublksrv_pid = -1; + + /* * 64bit flags will be copied back to userspace as feature * negotiation result, so have to clear flags which driver * doesn't support yet, then userspace can get correct flags