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.
Signed-off-by: Guo Zhi <[email protected]>
---
drivers/scsi/scsi_transport_iscsi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 922e4c7bd88e..7d6a570ebf48 100644
--- 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));
}
static DEVICE_ATTR(handle, S_IRUGO, show_transport_handle, NULL);
--
2.33.0
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);
?
I will send a V2 patch.
----- 原始邮件 -----
发件人: "Joe Perches" <[email protected]>
收件人: "Guo Zhi" <[email protected]>, "Lee Duncan" <[email protected]>, "Chris Leech" <[email protected]>, "James E.J. Bottomley" <[email protected]>, "Martin K. Petersen" <[email protected]>
抄送: [email protected], [email protected], "linux-kernel" <[email protected]>
发送时间: 星期六, 2021年 10 月 09日 上午 11:14:36
主题: Re: [PATCH] scsi scsi_transport_iscsi.c: fix misuse of %llu in scsi_transport_iscsi.c
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);
?
>>> 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?
>
> ?
>
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> 0b9ec95c.camel%40perches.com.
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.
>>> Mike Christie <[email protected]> schrieb am 11.10.2021 um 17:29 in
Nachricht <[email protected]>:
> 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.
I'm not in the details, but if that value is used as an ID, shouldn't it have been something like "ID%llu" right from the start?
If so it would be rather easy to use "ID%p" instead (if the syntax of the ID is left unspecified). At least nobody would treat it as a number.
Regards,
Ulrich
>
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> f46c%40oracle.com.
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