2021-11-12 21:47:16

by Stefano Stabellini

Subject: [PATCH] xen: don't continue xenstore initialization in case of errors

From: Stefano Stabellini <[email protected]>

In case of errors in xenbus_init (e.g. missing xen_store_gfn parameter),
we goto out_error but we forget to reset xen_store_domain_type to
XS_UNKNOWN. As a consequence xenbus_probe_initcall and other initcalls
will still try to initialize xenstore resulting into a crash at boot.

[ 2.479830] Call trace:
[ 2.482314] xb_init_comms+0x18/0x150
[ 2.486354] xs_init+0x34/0x138
[ 2.489786] xenbus_probe+0x4c/0x70
[ 2.498432] xenbus_probe_initcall+0x2c/0x7c
[ 2.503944] do_one_initcall+0x54/0x1b8
[ 2.507358] kernel_init_freeable+0x1ac/0x210
[ 2.511617] kernel_init+0x28/0x130
[ 2.516112] ret_from_fork+0x10/0x20

Cc: <[email protected]>
Signed-off-by: Stefano Stabellini <[email protected]>
---
drivers/xen/xenbus/xenbus_probe.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index bd003ca8acbe..34abf2b5967b 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -983,8 +983,10 @@ static int __init xenbus_init(void)
*/
proc_create_mount_point("xen");
#endif
+ return err;

out_error:
+ xen_store_domain_type = XS_UNKNOWN;
return err;
}

--
2.25.1

2021-11-15 10:08:30

by Jan Beulich

Subject: Re: [PATCH] xen: don't continue xenstore initialization in case of errors

On 12.11.2021 22:47, Stefano Stabellini wrote:
> --- a/drivers/xen/xenbus/xenbus_probe.c
> +++ b/drivers/xen/xenbus/xenbus_probe.c
> @@ -983,8 +983,10 @@ static int __init xenbus_init(void)
> */
> proc_create_mount_point("xen");
> #endif
> + return err;

Personally I think such cases would better be "return 0". With
that done here, err's initializer could (imo should) then also
be dropped.

Jan

> out_error:
> + xen_store_domain_type = XS_UNKNOWN;
> return err;
> }
>
>

2021-11-16 00:11:22

by Stefano Stabellini

Subject: Re: [PATCH] xen: don't continue xenstore initialization in case of errors

On Mon, 15 Nov 2021, Jan Beulich wrote:
> On 12.11.2021 22:47, Stefano Stabellini wrote:
> > --- a/drivers/xen/xenbus/xenbus_probe.c
> > +++ b/drivers/xen/xenbus/xenbus_probe.c
> > @@ -983,8 +983,10 @@ static int __init xenbus_init(void)
> > */
> > proc_create_mount_point("xen");
> > #endif
> > + return err;
>
> Personally I think such cases would better be "return 0". With
> that done here, err's initializer could (imo should) then also
> be dropped.

I'll make both changes in the next version


> > out_error:
> > + xen_store_domain_type = XS_UNKNOWN;
> > return err;
> > }
> >
> >
>