Re: [PATCH] NFSv4.2: fix nfs4_listxattr NULL pointer dereference

On Mon, Jul 6, 2026 at 5:55 PM Paul Moore <[email protected]> wrote:
>[...]

> I wonder if it would be better associate the handling code with the
> security_inode_listsecurity() call a bit more closely?  Thinking about
> it quickly, would something like what's below work?
>
>   left2 = left;
>   error2 = security_inode_listsecurity(..., &list, &left2);
>   if (error2 < 0)
>     return error2;
>   error2 = left - left2;
>   if (list)
>     left -= error2;

Yes, that works and is better than what I was proposing.
strace on my nfs mount:

    listxattr("/mnt/abc.txt", NULL, 0) = 26 <-- v1 patch, actual is 42
    listxattr("/mnt/abc.txt", NULL, 0) = 42 <-- with your changes

Tested your suggestion on v4.2 w/ an NFSv4 ACL, an SELinux label and a
user xattr present; both the size query and the exact-size read now
return 42.

Will send a v2 soon, thanks!

-Achilles