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[185.219.167.24]) by smtp.gmail.com with ESMTPSA id l6-20020a1c2506000000b0038e6fe8e8d8sm22732493wml.5.2022.04.11.03.12.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Apr 2022 03:12:59 -0700 (PDT) Message-ID: Date: Mon, 11 Apr 2022 12:12:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH] tty: synclink_gt: Fix null-pointer-dereference in slgt_clean() Content-Language: en-US To: Zheyu Ma , gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org References: <20220410114814.3920474-1-zheyuma97@gmail.com> From: Jiri Slaby In-Reply-To: <20220410114814.3920474-1-zheyuma97@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-3.0 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, NICE_REPLY_A,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10. 04. 22, 13:48, Zheyu Ma wrote: > When the driver fails at alloc_hdlcdev(), and then we remove the driver > module, we will get the following splat: > > [ 25.065966] general protection fault, probably for non-canonical address 0xdffffc0000000182: 0000 [#1] PREEMPT SMP KASAN PTI > [ 25.066914] KASAN: null-ptr-deref in range [0x0000000000000c10-0x0000000000000c17] > [ 25.069262] RIP: 0010:detach_hdlc_protocol+0x2a/0x3e0 > [ 25.077709] Call Trace: > [ 25.077924] > [ 25.078108] unregister_hdlc_device+0x16/0x30 > [ 25.078481] slgt_cleanup+0x157/0x9f0 [synclink_gt] > > Fix this by checking whether the 'info->netdev' is a null pointer first. Hi, LGTM Reviewed-by: Jiri Slaby Out of curiosity, do you use the driver, or you only do some static analysis? > Signed-off-by: Zheyu Ma > --- > drivers/tty/synclink_gt.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c > index 25c558e65ece..9bc2a9265277 100644 > --- a/drivers/tty/synclink_gt.c > +++ b/drivers/tty/synclink_gt.c > @@ -1746,6 +1746,8 @@ static int hdlcdev_init(struct slgt_info *info) > */ > static void hdlcdev_exit(struct slgt_info *info) > { > + if (!info->netdev) > + return; > unregister_hdlc_device(info->netdev); > free_netdev(info->netdev); > info->netdev = NULL; -- js suse labs