Do not try to refresh the RNG seed in case the firmware does not support
setting variables.
This is specifically needed to prevent a NULL-pointer dereference on the
Lenovo X13s with some firmware revisions, or more generally, whenever
the runtime services have been disabled (e.g. efi=noruntime or with
PREEMPT_RT).
Fixes: e7b813b32a42 ("efi: random: refresh non-volatile random seed when RNG is initialized")
Reported-by: Steev Klimaszewski <[email protected]>
Reported-by: Bjorn Andersson <[email protected]>
Tested-by: Andrew Halaney <[email protected]> # sc8280xp-lenovo-thinkpad-x13s
Signed-off-by: Johan Hovold <[email protected]>
---
Changes in v2
- amend commit message with a comment on this being needed whenever the
runtime services have been disabled
drivers/firmware/efi/efi.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 31a4090c66b3..09716eebe8ac 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -429,7 +429,9 @@ static int __init efisubsys_init(void)
platform_device_register_simple("efi_secret", 0, NULL, 0);
#endif
- execute_with_initialized_rng(&refresh_nv_rng_seed_nb);
+ if (efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))
+ execute_with_initialized_rng(&refresh_nv_rng_seed_nb);
+
return 0;
err_remove_group:
--
2.37.4
On Mon, Dec 19, 2022 at 03:00:17PM +0100, Jason A. Donenfeld wrote:
> On Mon, Dec 19, 2022 at 11:12:37AM +0100, Johan Hovold wrote:
> > Do not try to refresh the RNG seed in case the firmware does not support
> > setting variables.
> >
> > This is specifically needed to prevent a NULL-pointer dereference on the
> > Lenovo X13s with some firmware revisions, or more generally, whenever
> > the runtime services have been disabled (e.g. efi=noruntime or with
> > PREEMPT_RT).
> >
> > Fixes: e7b813b32a42 ("efi: random: refresh non-volatile random seed when RNG is initialized")
> > Reported-by: Steev Klimaszewski <[email protected]>
> > Reported-by: Bjorn Andersson <[email protected]>
> > Tested-by: Andrew Halaney <[email protected]> # sc8280xp-lenovo-thinkpad-x13s
> > Signed-off-by: Johan Hovold <[email protected]>
> > ---
> >
> > Changes in v2
> > - amend commit message with a comment on this being needed whenever the
> > runtime services have been disabled
>
> I'll queue up the one with the amended commit message.
Perfect, thanks!
Johan
On Mon, Dec 19, 2022 at 11:12:37AM +0100, Johan Hovold wrote:
> Do not try to refresh the RNG seed in case the firmware does not support
> setting variables.
>
> This is specifically needed to prevent a NULL-pointer dereference on the
> Lenovo X13s with some firmware revisions, or more generally, whenever
> the runtime services have been disabled (e.g. efi=noruntime or with
> PREEMPT_RT).
>
> Fixes: e7b813b32a42 ("efi: random: refresh non-volatile random seed when RNG is initialized")
> Reported-by: Steev Klimaszewski <[email protected]>
> Reported-by: Bjorn Andersson <[email protected]>
> Tested-by: Andrew Halaney <[email protected]> # sc8280xp-lenovo-thinkpad-x13s
> Signed-off-by: Johan Hovold <[email protected]>
> ---
>
> Changes in v2
> - amend commit message with a comment on this being needed whenever the
> runtime services have been disabled
I'll queue up the one with the amended commit message.
Jason
On Mon, Dec 19, 2022 at 4:13 AM Johan Hovold <[email protected]> wrote:
>
> Do not try to refresh the RNG seed in case the firmware does not support
> setting variables.
>
> This is specifically needed to prevent a NULL-pointer dereference on the
> Lenovo X13s with some firmware revisions, or more generally, whenever
> the runtime services have been disabled (e.g. efi=noruntime or with
> PREEMPT_RT).
>
> Fixes: e7b813b32a42 ("efi: random: refresh non-volatile random seed when RNG is initialized")
> Reported-by: Steev Klimaszewski <[email protected]>
> Reported-by: Bjorn Andersson <[email protected]>
> Tested-by: Andrew Halaney <[email protected]> # sc8280xp-lenovo-thinkpad-x13s
> Signed-off-by: Johan Hovold <[email protected]>
> ---
>
> Changes in v2
> - amend commit message with a comment on this being needed whenever the
> runtime services have been disabled
>
>
> drivers/firmware/efi/efi.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 31a4090c66b3..09716eebe8ac 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -429,7 +429,9 @@ static int __init efisubsys_init(void)
> platform_device_register_simple("efi_secret", 0, NULL, 0);
> #endif
>
> - execute_with_initialized_rng(&refresh_nv_rng_seed_nb);
> + if (efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))
> + execute_with_initialized_rng(&refresh_nv_rng_seed_nb);
> +
> return 0;
>
> err_remove_group:
> --
> 2.37.4
>
Andrew already sent one, but also confirming since I reported it, this
fixes the issue for me as well.
Tested-by: Steev Klimaszewski <[email protected]>