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Thu, 03 Aug 2023 02:07:11 -0700 (PDT) X-Google-Smtp-Source: APBJJlFbtYaRdfQiCCSsftcCDee+fV7mRevjzslMKuB3NaQ7j4mgPujTXQrdToxGjnhoy2l5oKCeqQ== X-Received: by 2002:a05:6512:3ae:b0:4f8:4177:e087 with SMTP id v14-20020a05651203ae00b004f84177e087mr5204391lfp.47.1691053631209; Thu, 03 Aug 2023 02:07:11 -0700 (PDT) Received: from localhost ([31.111.84.232]) by smtp.gmail.com with ESMTPSA id w6-20020aa7dcc6000000b005223ad8d7d7sm9803357edu.30.2023.08.03.02.07.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Aug 2023 02:07:10 -0700 (PDT) To: Tom Tromey , Andrew Burgess via Gdb-patches Subject: Re: [PATCH 1/2] gdb: fix possible nullptr dereference in a remote_debug_printf call In-Reply-To: <87y1jckkss.fsf@tromey.com> References: <5476235cc65b171f32663fa5e0af0a62342d1f63.1689690655.git.aburgess@redhat.com> <87y1jckkss.fsf@tromey.com> Date: Thu, 03 Aug 2023 10:07:09 +0100 Message-ID: <87jzucebpe.fsf@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-5.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP, 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 server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Andrew Burgess via Gdb-patches Reply-To: Andrew Burgess Errors-To: gdb-patches-bounces+public-inbox=simark.ca@sourceware.org Sender: "Gdb-patches" Tom Tromey writes: >>>>>> "Andrew" == Andrew Burgess via Gdb-patches writes: > > Andrew> While working on the next patch I triggered a segfault from within the > Andrew> function remote_target::discard_pending_stop_replies. Turns out this > Andrew> was caused by a cut&paste error introduced in this commit: > > Andrew> commit df5ad102009c41ab4dfadbb8cfb8c8b2a02a4f78 > Andrew> Date: Wed Dec 1 09:40:03 2021 -0500 > > Andrew> gdb, gdbserver: detach fork child when detaching from fork parent > > Andrew> This commit adds a remote_debug_printf call that was copied from > Andrew> earlier in the function, however, the new call wasn't updated to use > Andrew> the appropriate local variable. The local variable that it is using > Andrew> might be nullptr, in which case we trigger undefined behaviour, and > Andrew> could crash, which is what I was seeing. > > Andrew> Fixed by updating to use the correct local variable. > > Seems obvious to me FWIW. I updated the commit message to not mention "the next patch", and pushed this fix. Thanks, Andrew