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Tsirkin" , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Vivek Goyal , Dave Young , Thomas Huth , Cornelia Huck , Janosch Frank , Claudio Imbrenda , Eric Farman , Andrew Morton Subject: Re: [PATCH v1 03/11] fs/proc/vmcore: disallow vmcore modifications after the vmcore was opened Message-ID: References: <20241025151134.1275575-1-david@redhat.com> <20241025151134.1275575-4-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241025151134.1275575-4-david@redhat.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 X-Rspam-User: X-Rspamd-Queue-Id: 48934180016 X-Rspamd-Server: rspam11 X-Stat-Signature: 4tmmrmeti3qn5t1ygr3ba7qpkr79byn6 X-HE-Tag: 1732267012-38461 X-HE-Meta: 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 h2IwehUE asZblmRMvgjmgcIaeQX6ZxZvhj8NY2AJZXS3r5F0ZhOxAcl2ecPo0ziyG46UZld2P55I2HAi1mGncweWj9c/1nT7JJGcIkbhx7R8hjxk2uIgn44lxpEsK8W7wUnn6nt8gJwigiNkxrjG3fsp7SRXuPU04N0Ud5767EqOnqRMWMiVFMoAwSMU4I2NlWdkGGopwU7Zi7gXlWK5v8rZFuUSXMZQDFnau8uTWJkWL2uULbQrU0PS5Qx6EPC5KGYx2LcKKGEkTUqDj8GKK6agvVE6RGtOrBxPRJm/LpiEhHF8PWDW7J2lkRV3XBXnB77AkESHxgM6uoE1PnhVNzb7YIMT8Rjpd8C/Hz8hzfqMQ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/25/24 at 05:11pm, David Hildenbrand wrote: ......snip... > @@ -1482,6 +1470,10 @@ int vmcore_add_device_dump(struct vmcoredd_data *data) > return -EINVAL; > } > > + /* We'll recheck under lock later. */ > + if (data_race(vmcore_opened)) > + return -EBUSY; As I commented to patch 7, if vmcore is opened and closed after checking, do we need to give up any chance to add device dumping as below? fd = open(/proc/vmcore); ...do checking; close(fd); quit any device dump adding; run makedumpfile on s390; ->fd = open(/proc/vmcore); -> try to dump; ->close(fd); > + > if (!data || !strlen(data->dump_name) || > !data->vmcoredd_callback || !data->size) > return -EINVAL; > @@ -1515,12 +1507,16 @@ int vmcore_add_device_dump(struct vmcoredd_data *data) > dump->buf = buf; > dump->size = data_size; > > - /* Add the dump to driver sysfs list */ > + /* Add the dump to driver sysfs list and update the elfcore hdr */ > mutex_lock(&vmcore_mutex); > - list_add_tail(&dump->list, &vmcoredd_list); > - mutex_unlock(&vmcore_mutex); > + if (vmcore_opened) { > + ret = -EBUSY; > + goto out_err; > + } > > + list_add_tail(&dump->list, &vmcoredd_list); > vmcoredd_update_size(data_size); > + mutex_unlock(&vmcore_mutex); > return 0; > > out_err: > -- > 2.46.1 >