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Fri, 9 Jun 2023 22:59:40 -0400 (EDT) From: Demi Marie Obenour To: Dwaipayan Ray , Lukas Bulwahn , Joe Perches , Jonathan Corbet , Federico Vaga , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Lee Jones , Andy Lutomirski , Thomas Gleixner , Vincenzo Frascino , Petr Mladek , Steven Rostedt , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes Cc: Demi Marie Obenour , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org Subject: [PATCH 4/4] Strict XenStore entry parsing Date: Fri, 9 Jun 2023 22:57:59 -0400 Message-Id: <20230610025759.1813-4-demi@invisiblethingslab.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230610025759.1813-1-demi@invisiblethingslab.com> References: <20230610025759.1813-1-demi@invisiblethingslab.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_PASS,SPF_NONE, T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED 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 X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1768284420301284532?= X-GMAIL-MSGID: =?utf-8?q?1768284420301284532?= This uses the newly-introduced strict version of sscanf(). Signed-off-by: Demi Marie Obenour --- drivers/xen/xenbus/xenbus_xs.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c index 12e02eb01f5991b31db451cc57037205359b347f..88e94269c9221d16d1a97e59399058e870675729 100644 --- a/drivers/xen/xenbus/xenbus_xs.c +++ b/drivers/xen/xenbus/xenbus_xs.c @@ -569,16 +569,20 @@ int xenbus_scanf(struct xenbus_transaction t, const char *dir, const char *node, const char *fmt, ...) { va_list ap; - int ret; + int ret = 0; + unsigned int len; char *val; - val = xenbus_read(t, dir, node, NULL); + val = xenbus_read(t, dir, node, &len); if (IS_ERR(val)) return PTR_ERR(val); + if (strlen(val) != len) + goto bad; va_start(ap, fmt); - ret = vsscanf(val, fmt, ap); + ret = vsscanf_strict(val, fmt, ap); va_end(ap); +bad: kfree(val); /* Distinctive errno. */ if (ret == 0) @@ -636,15 +640,18 @@ int xenbus_gather(struct xenbus_transaction t, const char *dir, ...) while (ret == 0 && (name = va_arg(ap, char *)) != NULL) { const char *fmt = va_arg(ap, char *); void *result = va_arg(ap, void *); + unsigned len; char *p; - p = xenbus_read(t, dir, name, NULL); + p = xenbus_read(t, dir, name, &len); if (IS_ERR(p)) { ret = PTR_ERR(p); break; } - if (fmt) { - if (sscanf(p, fmt, result) == 0) + if (strlen(p) != len) + ret = -EINVAL; + else if (fmt) { + if (sscanf_strict(p, fmt, result) <= 0) ret = -EINVAL; kfree(p); } else