Re: [PATCH] x86/pm: Fix false positive kmemleak report in msr_build_context().

[Rafael J. Wysocki]

On Thu, Mar 14, 2024 at 4:05 PM Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
>
> On 3/14/24 07:26, Anton Altaparmakov wrote:
> >  /* image of the saved processor state */
> >  struct saved_context {
> > -     /*
> > -      * On x86_32, all segment registers except gs are saved at kernel
> > -      * entry in pt_regs.
> > -      */
> > -     u16 gs;
> >       unsigned long cr0, cr2, cr3, cr4;
> >       u64 misc_enable;
> >       struct saved_msrs saved_msrs;
> > @@ -27,6 +22,11 @@ struct saved_context {
> >       unsigned long tr;
> >       unsigned long safety;
> >       unsigned long return_address;
> > +     /*
> > +      * On x86_32, all segment registers except gs are saved at kernel
> > +      * entry in pt_regs.
> > +      */
> > +     u16 gs;
> >       bool misc_enable_saved;
> >  } __attribute__((packed));
>
> Isn't this just kinda poking at the symptoms?  This seems to be
> basically the exact same bug as b0b592cf08, just with a different source
> of unaligned structure members.
>
> There's nothing to keep folks from reintroducing these kinds of issues
> and evidently no way to detect when they happen without lengthy reproducers.

This change is fine with me FWIW, but I agree that making it for
kmemleak reasons feels kind of misguided.