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[188.193.250.66]) by smtp.gmail.com with ESMTPSA id r14-20020a05640251ce00b004186b7c1268sm889812edd.50.2022.03.16.05.38.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Mar 2022 05:38:36 -0700 (PDT) Message-ID: <75409cc9-1e51-77d6-cbf2-6eccdbc53f1a@gmail.com> Date: Wed, 16 Mar 2022 13:38:35 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH 1/2] scsi: target: tcmu: Fix possible page UAF Content-Language: en-US To: Xiaoguang Wang , linux-scsi@vger.kernel.org, target-devel@vger.kernel.org References: <20220311132206.24515-1-xiaoguang.wang@linux.alibaba.com> From: Bodo Stroesser In-Reply-To: <20220311132206.24515-1-xiaoguang.wang@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: target-devel@vger.kernel.org This one looks good. Thank you. Reviewed-by: Bodo Stroesser On 11.03.22 14:22, Xiaoguang Wang wrote: > tcmu_try_get_data_page() looks up pages under cmdr_lock, but it don't > take refcount properly and just return page pointer. > > When tcmu_try_get_data_page() returns, the returned page may have been > freed by tcmu_blocks_release(), need to get_page() under cmdr_lock to > avoid concurrent tcmu_blocks_release(). > > Signed-off-by: Xiaoguang Wang > --- > drivers/target/target_core_user.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c > index 7b2a89a67cdb..06a5c4086551 100644 > --- a/drivers/target/target_core_user.c > +++ b/drivers/target/target_core_user.c > @@ -1820,6 +1820,7 @@ static struct page *tcmu_try_get_data_page(struct tcmu_dev *udev, uint32_t dpi) > mutex_lock(&udev->cmdr_lock); > page = xa_load(&udev->data_pages, dpi); > if (likely(page)) { > + get_page(page); > mutex_unlock(&udev->cmdr_lock); > return page; > } > @@ -1876,6 +1877,7 @@ static vm_fault_t tcmu_vma_fault(struct vm_fault *vmf) > /* For the vmalloc()ed cmd area pages */ > addr = (void *)(unsigned long)info->mem[mi].addr + offset; > page = vmalloc_to_page(addr); > + get_page(page); > } else { > uint32_t dpi; > > @@ -1886,7 +1888,6 @@ static vm_fault_t tcmu_vma_fault(struct vm_fault *vmf) > return VM_FAULT_SIGBUS; > } > > - get_page(page); > vmf->page = page; > return 0; > }