[adding back linux-arm-kernel; what happened to it? ]
On 5/17/21 2:04 PM, Randy Dunlap wrote:
> On 5/17/21 10:13 AM, Steve French wrote:
>>> If you fix the issue, kindly add following tag as appropriate
>>> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>>>
>>> All errors (new ones prefixed by >>):
>>>
>>> arm-linux-gnueabi-ld: fs/cifs/ioctl.o: in function `cifs_dump_full_key':
>>>>> ioctl.c:(.text+0x44): undefined reference to `__get_user_bad'
>>>
>>
>> <snip>
>>
>>> # CONFIG_MMU is not set
>>>
>>> and arch/arm/include/asm/uaccess.h does not implement get_user(size 8 bytes)
>>> for the non-MMU case:
>>
>> I see another place in fs/cifs/ioctl.c where we already had been doing
>> a get_user() into a u64 - any idea what you are supposed to do
>> instead? Any example code where people have worked around this.
>
> Hi Steve,
>
> This change in cifs_dump_full_key() makes it build OK:
>
> - if (get_user(suid, (__u64 __user *)arg))
> + if (get_user(suid, (unsigned int __user *)arg))
>
>
> That is what the other call uses:
>
> case FS_IOC_SETFLAGS:
> cifs_dbg(VFS, "cifs ioctl FS_IOC_SETFLAGS:\n");
> if (pSMBFile == NULL)
> break;
> tcon = tlink_tcon(pSMBFile->tlink);
> caps = le64_to_cpu(tcon->fsUnixInfo.Capability);
>
> if (get_user(ExtAttrBits, (int __user *)arg)) {
> rc = -EFAULT;
> break;
> }
>
> However, my reading/understanding is that the one immediately above
> is incorrect, as is the -/+ patch above it, since get_user() gets its
> data size (1, 2, 4, 8) from the type of the pointer that is passed to it.
> For 8 bytes (64 bits), 'int' is not sufficient, so IMO the get_user()
> call that builds:
> if (get_user(ExtAttrBits, (int __user *)arg)) {
> is a bug. It should be:
> if (get_user(ExtAttrBits, (__u64 __user *)arg)) {
> and if I make that latter change in the source file, the build says:
>
> arm-linux-gnueabi-ld: fs/cifs/ioctl.o: in function `cifs_dump_full_key':
> ioctl.c:(.text+0x14): undefined reference to `__get_user_bad'
> arm-linux-gnueabi-ld: fs/cifs/ioctl.o: in function `cifs_ioctl':
> ioctl.c:(.text+0x1f2): undefined reference to `__get_user_bad'
>
> so now both of them fail on the get_user() of 8 bytes.
>
> Hope that clarifies things. It tells me that arm no-MMU still
> needs support for get_user() of size 8 bytes.
>
--
~Randy
