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[24.9.64.241]) by smtp.gmail.com with ESMTPSA id i20sm64297ook.12.2021.07.28.09.37.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Jul 2021 09:37:39 -0700 (PDT) Subject: Re: [PATCH v8 2/2] firmware_loader: fix use-after-free in firmware_fallback_sysfs To: Anirudh Rayabharam , mcgrof@kernel.org, gregkh@linuxfoundation.org, rafael@kernel.org Cc: linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, syzbot+de271708674e2093097b@syzkaller.appspotmail.com, Shuah Khan References: <20210728085107.4141-1-mail@anirudhrb.com> <20210728085107.4141-3-mail@anirudhrb.com> From: Shuah Khan Message-ID: Date: Wed, 28 Jul 2021 10:37:38 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210728085107.4141-3-mail@anirudhrb.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/28/21 2:51 AM, Anirudh Rayabharam wrote: > This use-after-free happens when a fw_priv object has been freed but > hasn't been removed from the pending list (pending_fw_head). The next > time fw_load_sysfs_fallback tries to insert into the list, it ends up > accessing the pending_list member of the previously freed fw_priv. > > The root cause here is that all code paths that abort the fw load > don't delete it from the pending list. For example: > > _request_firmware() > -> fw_abort_batch_reqs() > -> fw_state_aborted() > > To fix this, delete the fw_priv from the list in __fw_set_state() if > the new state is DONE or ABORTED. This way, all aborts will remove > the fw_priv from the list. Accordingly, remove calls to list_del_init > that were being made before calling fw_state_(aborted|done). > > Also, in fw_load_sysfs_fallback, don't add the fw_priv to the pending > list if it is already aborted. Instead, just jump out and return early. > > Fixes: bcfbd3523f3c ("firmware: fix a double abort case with fw_load_sysfs_fallback") > Reported-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com > Tested-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com > Acked-by: Luis Chamberlain > Signed-off-by: Anirudh Rayabharam > --- > drivers/base/firmware_loader/fallback.c | 12 ++++++++---- > drivers/base/firmware_loader/firmware.h | 10 +++++++++- > drivers/base/firmware_loader/main.c | 2 ++ > 3 files changed, 19 insertions(+), 5 deletions(-) > Thank you. Looks good. Reviewed-by: Shuah Khan thanks, -- Shuah