git: 47f7345baba0 - main - linux: fix PTRACE_POKEDATA and PTRACE_POKETEXT.

[Edward Tomasz Napierala]

On 0119T1314, Konstantin Belousov wrote:
> On Tue, Jan 19, 2021 at 10:53:38AM +0000, Edward Tomasz Napierala wrote:
> > The branch main has been updated by trasz:
> > 
> > URL: https://cgit.FreeBSD.org/src/commit/?id=47f7345baba01121e29c22b43f68345399a32912
> > 
> > commit 47f7345baba01121e29c22b43f68345399a32912
> > Author:     Edward Tomasz Napierala <trasz at FreeBSD.org>
> > AuthorDate: 2021-01-15 16:57:24 +0000
> > Commit:     Edward Tomasz Napierala <trasz at FreeBSD.org>
> > CommitDate: 2021-01-19 10:30:55 +0000
> > 
> >     linux: fix PTRACE_POKEDATA and PTRACE_POKETEXT.
> >     
> >     Sponsored by:   The FreeBSD Foundation
> > ---
> >  sys/amd64/linux/linux_ptrace.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/sys/amd64/linux/linux_ptrace.c b/sys/amd64/linux/linux_ptrace.c
> > index a14155ed7e97..c1d05db5bc42 100644
> > --- a/sys/amd64/linux/linux_ptrace.c
> > +++ b/sys/amd64/linux/linux_ptrace.c
> > @@ -594,10 +594,15 @@ linux_ptrace(struct thread *td, struct linux_ptrace_args *uap)
> >  		error = linux_ptrace_peekuser(td, pid, addr, (void *)uap->data);
> >  		break;
> >  	case LINUX_PTRACE_POKETEXT:
> > -		error = kern_ptrace(td, PT_WRITE_I, pid, addr, uap->data);
> > -		break;
> This is wrong. You should access text AS if linux request was for text.

Do we actually want to maintain that distinction?  Looking
at sys/kern/sys_process.c, they are synonyms.

> >  	case LINUX_PTRACE_POKEDATA:
> >  		error = kern_ptrace(td, PT_WRITE_D, pid, addr, uap->data);
> > +		if (error != 0)
> > +			return (error);
> > +		/*
> > +		 * Linux expects this syscall to write 64 bits, not 32.
> > +		 */
> > +		error = kern_ptrace(td, PT_WRITE_D, pid,
> > +		    (void *)(uap->addr + 4), uap->data >> 32);
> >  		break;
> You should use PT_IO there instead of doing two accesses (to the wrong AS).

Hm, you're right.  The only problem I can see is that PT_IO fetches
struct ptrace_io_desc from userspace, which makes wrapping somewhat
hard.  How about introducing PT_READ64 and PT_WRITE64 request types
and using them instead?

Thanks!