| Message ID | 20221216091514.6298-1-johan+linaro@kernel.org |
|---|---|
| State | Accepted |
| Commit | 41a15855c1ee390a0ae9d0c29d32b451dd30a600 |
| Headers | show |
| Series | efi: random: fix NULL-deref when refreshing seed | expand |
On Fri, Dec 16, 2022 at 10:15:14AM +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. > > Fixes: e7b813b32a42 ("efi: random: refresh non-volatile random seed when RNG is initialized") > Reported-by: Steev Klimaszewski <steev@kali.org> > Reported-by: Bjorn Andersson <andersson@kernel.org> > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > --- Thanks very much for this, and sorry for the breakage. I'll try to get this in before rc1 is cut, as I've got some other changes scheduled for late in the merge window to send anyway. Jason
On Fri, Dec 16, 2022 at 12:39:56PM -0700, Jason A. Donenfeld wrote: > On Fri, Dec 16, 2022 at 10:15:14AM +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. > > > > Fixes: e7b813b32a42 ("efi: random: refresh non-volatile random seed when RNG is initialized") > > Reported-by: Steev Klimaszewski <steev@kali.org> > > Reported-by: Bjorn Andersson <andersson@kernel.org> > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > > --- > > Thanks very much for this, and sorry for the breakage. I'll try to get > this in before rc1 is cut, as I've got some other changes scheduled for > late in the merge window to send anyway. In case this one hasn't been picked up yet (it's not in linux-next), I just sent a v2 with an amended commit message with an explicit mention that as this is needed whenever the runtime services have been disabled (e.g. with PREEMPT_RT): https://lore.kernel.org/lkml/20221219101237.9872-1-johan+linaro@kernel.org/ Johan
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 2e168e5b97de..1a9e2f70c550 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -432,7 +432,9 @@ 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:
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. Fixes: e7b813b32a42 ("efi: random: refresh non-volatile random seed when RNG is initialized") Reported-by: Steev Klimaszewski <steev@kali.org> Reported-by: Bjorn Andersson <andersson@kernel.org> Signed-off-by: Johan Hovold <johan+linaro@kernel.org> --- drivers/firmware/efi/efi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)