On 10/03/2021 10:13, Jan Beulich wrote:
> Sadly I was wrong to suggest dropping vaddrs' initializer during review
> of v2 of the patch introducing this code. gcc 4.3 can't cope.
>
> Fixes: 52531c734ea1 ("xen/gnttab: Rework resource acquisition")
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
>
> --- a/xen/common/grant_table.c
> +++ b/xen/common/grant_table.c
> @@ -4026,7 +4026,7 @@ int gnttab_acquire_resource(
> struct grant_table *gt = d->grant_table;
> unsigned int i, final_frame;
> mfn_t tmp;
> - void **vaddrs;
> + void **vaddrs = NULL;
> int rc = -EINVAL;
>
> if ( !nr_frames )
in v1, there was a companion check.
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index f937c1d350..2bb07f129f 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -4059,6 +4059,16 @@ int gnttab_acquire_resource(
if ( rc )
goto out;
+ /*
+ * Some older toolchains can't spot that vaddrs is non-NULL on
non-error
+ * paths. Leave some runtime safety.
+ */
+ if ( !vaddrs )
+ {
+ ASSERT_UNREACHABLE();
+ goto out;
+ }
+
for ( i = 0; i < nr_frames; ++i )
mfn_list[i] = virt_to_mfn(vaddrs[frame + i]);
With this reinstated, Acked-by: Andrew Cooper <andrew.coop...@citrix.com>
