On Fri, Dec 17, 2021 at 02:31:53PM -0800, Dave Hansen wrote: > > 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. > > Add a check to ensure that SGX has been initialized to the point > where sgx_numa_nodes[] is allocated, before accessing it. > > 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> Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx> > --- > > b/arch/x86/kernel/cpu/sgx/main.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > 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 2021-12-17 13:38:00.217312383 -0800 > +++ b/arch/x86/kernel/cpu/sgx/main.c 2021-12-17 14:00:36.293044390 -0800 > @@ -906,7 +906,13 @@ EXPORT_SYMBOL_GPL(sgx_set_attribute); > #ifdef CONFIG_NUMA > static ssize_t sgx_total_bytes_show(struct device *dev, struct device_attribute *attr, char *buf) > { > - return sysfs_emit(buf, "%lu\n", sgx_numa_nodes[dev->id].size); > + unsigned long node_bytes = 0; > + > + /* Avoid acccessing sgx_numa_nodes[] when it is not allocated: */ > + if (!nodes_empty(sgx_numa_mask)) > + node_bytes = sgx_numa_nodes[dev->id].size; > + > + return sysfs_emit(buf, "%lu\n", node_bytes); > } > static DEVICE_ATTR_RO(sgx_total_bytes); > > _
