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[72.132.29.68]) by smtp.gmail.com with ESMTPSA id h8sm5800635pgr.43.2021.06.08.14.26.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Jun 2021 14:26:31 -0700 (PDT) Subject: Re: [PATCH v2] libnvdimm/pmem: Fix blk_cleanup_disk() usage To: Dan Williams Cc: Sachin Sant , Christoph Hellwig , Ulf Hansson , nvdimm@lists.linux.dev, linux-block@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <162310861219.1571453.6561642225122047071.stgit@dwillia2-desk3.amr.corp.intel.com> <162310994435.1571616.334551212901820961.stgit@dwillia2-desk3.amr.corp.intel.com> From: Jens Axboe Message-ID: <1b2082fc-be01-ad2f-9dd5-aa66b1c0ce85@kernel.dk> Date: Tue, 8 Jun 2021 15:26:50 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <162310994435.1571616.334551212901820961.stgit@dwillia2-desk3.amr.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 6/7/21 5:52 PM, Dan Williams wrote: > The queue_to_disk() helper can not be used after del_gendisk() > communicate @disk via the pgmap->owner. > > Otherwise, queue_to_disk() returns NULL resulting in the splat below. > > Kernel attempted to read user page (330) - exploit attempt? (uid: 0) > BUG: Kernel NULL pointer dereference on read at 0x00000330 > Faulting instruction address: 0xc000000000906344 > Oops: Kernel access of bad area, sig: 11 [#1] > [..] > NIP [c000000000906344] pmem_pagemap_cleanup+0x24/0x40 > LR [c0000000004701d4] memunmap_pages+0x1b4/0x4b0 > Call Trace: > [c000000022cbb9c0] [c0000000009063c8] pmem_pagemap_kill+0x28/0x40 (unreliable) > [c000000022cbb9e0] [c0000000004701d4] memunmap_pages+0x1b4/0x4b0 > [c000000022cbba90] [c0000000008b28a0] devm_action_release+0x30/0x50 > [c000000022cbbab0] [c0000000008b39c8] release_nodes+0x2f8/0x3e0 > [c000000022cbbb60] [c0000000008ac440] device_release_driver_internal+0x190/0x2b0 > [c000000022cbbba0] [c0000000008a8450] unbind_store+0x130/0x170 Applied, thanks. -- Jens Axboe