[PATCH] d3dcompiler: Iterate through the instruction list in reverse in free_instr_list() (Valgrind).

[Zebediah Figura]

To avoid heap corruption when unlinking the instruction from the "uses" list.

Signed-off-by: Zebediah Figura <z.figura12(a)gmail.com>
---
Alternatively, we could make unlinking into a separate operation.

 dlls/d3dcompiler_43/utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/d3dcompiler_43/utils.c b/dlls/d3dcompiler_43/utils.c
index e8bdbea7e13..ac5722e11aa 100644
--- a/dlls/d3dcompiler_43/utils.c
+++ b/dlls/d3dcompiler_43/utils.c
@@ -1937,7 +1937,7 @@ void free_instr_list(struct list *list)
 
     if (!list)
         return;
-    LIST_FOR_EACH_ENTRY_SAFE(node, next_node, list, struct hlsl_ir_node, entry)
+    LIST_FOR_EACH_ENTRY_SAFE_REV(node, next_node, list, struct hlsl_ir_node, entry)
         free_instr(node);
     d3dcompiler_free(list);
 }
-- 
2.27.0

[Matteo Bruni]

On Wed, Aug 5, 2020 at 6:31 PM Zebediah Figura <z.figura12(a)gmail.com> wrote:
> To avoid heap corruption when unlinking the instruction from the "uses" list.
>
> Signed-off-by: Zebediah Figura <z.figura12(a)gmail.com>
> ---
> Alternatively, we could make unlinking into a separate operation.
>
> dlls/d3dcompiler_43/utils.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/dlls/d3dcompiler_43/utils.c b/dlls/d3dcompiler_43/utils.c
> index e8bdbea7e13..ac5722e11aa 100644
> --- a/dlls/d3dcompiler_43/utils.c
> +++ b/dlls/d3dcompiler_43/utils.c
> @@ -1937,7 +1937,7 @@ void free_instr_list(struct list *list)
>
> if (!list)
>          return;
> -    LIST_FOR_EACH_ENTRY_SAFE(node, next_node, list, struct hlsl_ir_node, entry)
> +    LIST_FOR_EACH_ENTRY_SAFE_REV(node, next_node, list, struct hlsl_ir_node, entry)
>          free_instr(node);
>      d3dcompiler_free(list);
>  }

Freeing in reverse should be fine but I think it deserves a comment in
the code, this is definitely not obvious.

[Zebediah Figura]

On 8/10/20 10:42 AM, Matteo Bruni wrote:
> On Wed, Aug 5, 2020 at 6:31 PM Zebediah Figura <z.figura12(a)gmail.com> wrote:
> > To avoid heap corruption when unlinking the instruction from the "uses" list.
> >
> > Signed-off-by: Zebediah Figura <z.figura12(a)gmail.com>
> > ---
> > Alternatively, we could make unlinking into a separate operation.
> >
> > dlls/d3dcompiler_43/utils.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/dlls/d3dcompiler_43/utils.c b/dlls/d3dcompiler_43/utils.c
> > index e8bdbea7e13..ac5722e11aa 100644
> > --- a/dlls/d3dcompiler_43/utils.c
> > +++ b/dlls/d3dcompiler_43/utils.c
> > @@ -1937,7 +1937,7 @@ void free_instr_list(struct list *list)
> >
> > if (!list)
> >          return;
> > -    LIST_FOR_EACH_ENTRY_SAFE(node, next_node, list, struct hlsl_ir_node, entry)
> > +    LIST_FOR_EACH_ENTRY_SAFE_REV(node, next_node, list, struct hlsl_ir_node, entry)
> >          free_instr(node);
> >      d3dcompiler_free(list);
> >  }
>
> Freeing in reverse should be fine but I think it deserves a comment in
> the code, this is definitely not obvious.

Agreed, good point.