Re: [PATCH net-next v3 3/3] eventpoll: Add epoll ioctl for epoll_params

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, Jan 26, 2024, at 03:36, Joe Damato wrote:
> On Thu, Jan 25, 2024 at 04:23:58PM -0800, Greg Kroah-Hartman wrote:
>> On Thu, Jan 25, 2024 at 04:11:28PM -0800, Joe Damato wrote:
>> > On Thu, Jan 25, 2024 at 03:21:46PM -0800, Greg Kroah-Hartman wrote:
>> > > On Thu, Jan 25, 2024 at 10:56:59PM +0000, Joe Damato wrote:
>> > > > +struct epoll_params {
>> > > > +	u64 busy_poll_usecs;
>> > > > +	u16 busy_poll_budget;
>> > > > +
>> > > > +	/* for future fields */
>> > > > +	u8 data[118];
>> > > > +} EPOLL_PACKED;
>> > > 
>
> Sure, that makes sense to me. I'll remove it in the v4 alongside the other
> changes you've requested.
>
> Thanks for your time and patience reviewing my code. I greatly appreciate
> your helpful comments and feedback.

Note that you should still pad the structure to its normal
alignment. On non-x86 targets this would currently mean a
multiple of 64 bits.

I would suggest dropping the EPOLL_PACKED here entirely and
just using a fully aligned structure on all architectures, like

struct epoll_params {
      __aligned_u64 busy_poll_usecs;
      __u16 busy_poll_budget;
      __u8 __pad[6];
};

The explicit padding can help avoid leaking stack data when
a structure is copied back from kernel to userspace, so I would
just always use it in ioctl data structures.

      Arnd




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [NTFS 3]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [NTFS 3]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux