On Fri 20-12-19 16:06:05, Alexey Kardashevskiy wrote:
>
>
> On 11/12/2019 21:42, Jan Kara wrote:
> > The last jump to free_exit in mm_iommu_do_alloc() happens after page
> > pointers in struct mm_iommu_table_group_mem_t were already converted to
> > physical addresses. Thus calling put_page() on these physical addresses
> > will likely crash. Convert physical addresses back to page pointers
> > during the error cleanup.
> >
> > Signed-off-by: Jan Kara <j...@suse.cz>
> > ---
> > arch/powerpc/mm/book3s64/iommu_api.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > Beware, this is completely untested, spotted just by code audit.
> >
> > diff --git a/arch/powerpc/mm/book3s64/iommu_api.c
> > b/arch/powerpc/mm/book3s64/iommu_api.c
> > index 56cc84520577..06c403381c9c 100644
> > --- a/arch/powerpc/mm/book3s64/iommu_api.c
> > +++ b/arch/powerpc/mm/book3s64/iommu_api.c
> > @@ -154,7 +154,7 @@ static long mm_iommu_do_alloc(struct mm_struct *mm,
> > unsigned long ua,
> > (mem2->entries << PAGE_SHIFT)))) {
> > ret = -EINVAL;
> > mutex_unlock(&mem_list_mutex);
> > - goto free_exit;
> > + goto convert_exit;
> > }
> > }
> >
> > @@ -166,6 +166,9 @@ static long mm_iommu_do_alloc(struct mm_struct *mm,
> > unsigned long ua,
> >
> > return 0;
> >
> > +convert_exit:
> > + for (i = 0; i < pinned; i++)
> > + mem->hpages[i] = pfn_to_page(mem->hpas[i] >> PAGE_SHIFT);
>
>
> Good find. Although doing it where you added "goto convert_exit" seems
> cleaner imho. Thanks,
I don't really care :). V2 attached.
Honza
--
Jan Kara <j...@suse.com>
SUSE Labs, CR
>From 947c7a893c282b829a8623da73276a2fe56fdcd3 Mon Sep 17 00:00:00 2001
From: Jan Kara <j...@suse.cz>
Date: Wed, 11 Dec 2019 11:36:54 +0100
Subject: [PATCH v2] powerpc/book3s64: Fix error handling in mm_iommu_do_alloc()
The last jump to free_exit in mm_iommu_do_alloc() happens after page
pointers in struct mm_iommu_table_group_mem_t were already converted to
physical addresses. Thus calling put_page() on these physical addresses
will likely crash. Convert physical addresses back to page pointers
during the error cleanup.
Signed-off-by: Jan Kara <j...@suse.cz>
---
arch/powerpc/mm/book3s64/iommu_api.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/powerpc/mm/book3s64/iommu_api.c b/arch/powerpc/mm/book3s64/iommu_api.c
index 56cc84520577..1aa06584d783 100644
--- a/arch/powerpc/mm/book3s64/iommu_api.c
+++ b/arch/powerpc/mm/book3s64/iommu_api.c
@@ -154,6 +154,11 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
(mem2->entries << PAGE_SHIFT)))) {
ret = -EINVAL;
mutex_unlock(&mem_list_mutex);
+ /* Convert back to page pointers */
+ for (i = 0; i < pinned; i++) {
+ mem->hpages[i] =
+ pfn_to_page(mem->hpas[i] >> PAGE_SHIFT);
+ }
goto free_exit;
}
}
--
2.16.4
