Re: [PATCH][next] mm/vmalloc: Fix read of pointer area after it has been free'd

From: Uladzislau Rezki
Date: Mon Mar 29 2021 - 14:31:21 EST


On Mon, Mar 29, 2021 at 08:14:53PM +0200, Uladzislau Rezki wrote:
> On Mon, Mar 29, 2021 at 07:40:29PM +0200, Uladzislau Rezki wrote:
> > On Mon, Mar 29, 2021 at 06:14:34PM +0100, Matthew Wilcox wrote:
> > > On Mon, Mar 29, 2021 at 06:07:30PM +0100, Colin King wrote:
> > > > From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> > > >
> > > > Currently the memory pointed to by area is being freed by the
> > > > free_vm_area call and then area->nr_pages is referencing the
> > > > free'd object. Fix this swapping the order of the warn_alloc
> > > > message and the free.
> > > >
> > > > Addresses-Coverity: ("Read from pointer after free")
> > > > Fixes: 014ccf9b888d ("mm/vmalloc: improve allocation failure error messages")
> > >
> > > i don't have this git sha. if this is -next, the sha ids aren't stable
> > > and shouldn't be referenced in commit logs, because these fixes should
> > > just be squashed into the not-yet-upstream commits.
> > >
> > > > Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> > > > ---
> > > > mm/vmalloc.c | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > > > index b73e4e715e0d..7936405749e4 100644
> > > > --- a/mm/vmalloc.c
> > > > +++ b/mm/vmalloc.c
> > > > @@ -2790,11 +2790,11 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
> > > > }
> > > >
> > > > if (!pages) {
> > > > - free_vm_area(area);
> > > > warn_alloc(gfp_mask, NULL,
> > > > "vmalloc size %lu allocation failure: "
> > > > "page array size %lu allocation failed",
> > > > area->nr_pages * PAGE_SIZE, array_size);
> > > > + free_vm_area(area);
> > > > return NULL;
> > >
> > > this fix looks right to me.
> > >
> > That is from the linux-next. Same to me.
> >
> > Reviewed-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> >
> > --
> > Vlad Rezki
> Is the linux-next(next-20210329) broken?
>
Please ignore my previous email. That was due to my local "stashed" change.

--
Vlad Rezki