On 2021/10/11 23:29, Mike Christie wrote:
On 10/11/21 1:35 AM, Ulrich Windl wrote:
Joe Perches <[email protected]> schrieb am 09.10.2021 um 05:14 in Nachricht
<[email protected]>:
On Sat, 2021-10-09 at 11:02 +0800, Guo Zhi wrote:
Pointers should be printed with %p or %px rather than
cast to (unsigned long long) and printed with %llu.
Change %llu to %p to print the pointer into sysfs.
][]
diff --git a/drivers/scsi/scsi_transport_iscsi.c
b/drivers/scsi/scsi_transport_iscsi.c
[]
@@ -129,8 +129,8 @@ show_transport_handle(struct device *dev, struct
device_attribute *attr,
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
-       return sysfs_emit(buf, "%llu\n",
-                 (unsigned long long)iscsi_handle(priv->iscsi_transport));
+       return sysfs_emit(buf, "%p\n",
+               iscsi_ptr(priv->iscsi_transport));
iscsi_transport is a pointer isn't it?

so why not just

        return sysfs_emit(buf, "%p\n", priv->iscsi_transport);
Isn't the difference that %p outputs hex, while %u outputs decimal?

Yeah, I think this patch will break userspace, because it doesn't know it's
a pointer. It could be doing:

sscanf(str, "%llu", &val);

The value is just later passed back to the kernel to look up a driver in
iscsi_if_transport_lookup:

         list_for_each_entry(priv, &iscsi_transports, list) {
                 if (tt == priv->iscsi_transport) {

so we could just replace priv->transport with an int and use an ida to assign
the value.

Taking security into consideration, We should not print kernel pointer into sysfs.

However if this is a special pointer to lookup a driver,  It's really tricky for me to fix it,

as I don't have a scsi device to test my code.


Guo


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