On Thu, Jan 06, 2022 at 09:18:35PM +0200, Jarkko Sakkinen wrote: > On Sat, Jan 01, 2022 at 08:54:51PM -0800, Dave Hansen wrote: > > On 12/28/21 3:45 PM, Jarkko Sakkinen wrote: > > >> If I can provide any further information or testing, let me know! > > > Dave, when is the fix going to be applied [*]? > > > > > >> Cheers, > > >> Nathan > > > [*] https://lore.kernel.org/linux-sgx/YcGTePmWDMOQU1pn@xxxxxx/T/#m831a01bdde347f9e0af2c973986fae0499718201 > > > > Greg preferred hiding the file as opposed to faking a number in there. > > Any testing of the attached would be appreciated. > > > > > From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > > > Nathan Chancellor reported an oops when aceessing the > > 'sgx_total_bytes' sysfs file: > > > > https://lore.kernel.org/all/YbzhBrimHGGpddDM@archlinux-ax161/ > > > > The sysfs output code accesses the sgx_numa_nodes[] array > > unconditionally. However, this array is allocated during SGX > > initialization, which only occurs on systems where SGX is > > supported. > > > > If the sysfs file is accessed on systems without SGX support, > > sgx_numa_nodes[] is NULL and an oops occurs. > > > > To fix this, hide the entire nodeX/x86/ attribute group on > > systems without SGX support using the ->is_visible attribute > > group callback. > > > > Fixes: 50468e431335 ("x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node") > > Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx> > > CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > > Cc: linux-sgx@xxxxxxxxxxxxxxx > > Cc: x86@xxxxxxxxxx > > Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > --- > > > > b/arch/x86/kernel/cpu/sgx/main.c | 11 +++++++++++ > > 1 file changed, 11 insertions(+) > > > > diff -puN arch/x86/kernel/cpu/sgx/main.c~sgx-null-ptr arch/x86/kernel/cpu/sgx/main.c > > --- a/arch/x86/kernel/cpu/sgx/main.c~sgx-null-ptr 2021-12-20 07:56:38.309584807 -0800 > > +++ b/arch/x86/kernel/cpu/sgx/main.c 2021-12-20 08:17:28.997705149 -0800 > > @@ -910,6 +910,16 @@ static ssize_t sgx_total_bytes_show(stru > > } > > static DEVICE_ATTR_RO(sgx_total_bytes); > > > > +static umode_t arch_node_attr_is_visible(struct kobject * kobj, > > + struct attribute * attr, int idx) > > +{ > > + /* Make all x86/ attributes invisible when SGX is not initialized: */ > > + if (nodes_empty(sgx_numa_mask)) > > + return 0; > > + > > + return attr->mode; > > +} > > + > > static struct attribute *arch_node_dev_attrs[] = { > > &dev_attr_sgx_total_bytes.attr, > > NULL, > > @@ -918,6 +928,7 @@ static struct attribute *arch_node_dev_a > > const struct attribute_group arch_node_dev_group = { > > .name = "x86", > > .attrs = arch_node_dev_attrs, > > + .is_visible = arch_node_attr_is_visible, > > }; > > #endif /* CONFIG_NUMA */ > > > > _ > > I'm compiling now kernel with this applied, reporting soon but the fix > looks good to me. Tested-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> Did two tests in a virtual machine: 1. Without the patch reproduced the crash. 2. With the patch verified that the crash does not occur. /Jarkko
