On Wed, Apr 7, 2021 at 11:32 PM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > All of the CPPC sysfs show functions are called via indirect call in > kobj_attr_show(), where they should be of type > > ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *attr, char *buf); > > because that is the type of the ->show() member in > 'struct kobj_attribute' but they are actually of type > > ssize_t (*show)(struct kobject *kobj, struct attribute *attr, char *buf); > > because of the ->show() member in 'struct cppc_attr', resulting in a > Control Flow Integrity violation [1]. > > $ cat /sys/devices/system/cpu/cpu0/acpi_cppc/highest_perf > 3400 > > $ dmesg | grep "CFI failure" > [ 175.970559] CFI failure (target: show_highest_perf+0x0/0x8): > > As far as I can tell, the only different between 'struct cppc_attr' and > 'struct kobj_attribute' aside from the type of the attr parameter is the > type of the count parameter in the ->store() member (ssize_t vs. > size_t), which does not actually matter because all of these nodes are > read-only. > > Eliminate 'struct cppc_attr' in favor of 'struct kobj_attribute' to fix > the violation. > > [1]: https://lore.kernel.org/r/20210401233216.2540591-1-samitolvanen@xxxxxxxxxx/ > > Fixes: 158c998ea44b ("ACPI / CPPC: add sysfs support to compute delivered performance") > Link: https://github.com/ClangBuiltLinux/linux/issues/1343 > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> > --- > drivers/acpi/cppc_acpi.c | 14 +++----------- > 1 file changed, 3 insertions(+), 11 deletions(-) > > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c > index 69057fcd2c04..a5e6fd0bafa1 100644 > --- a/drivers/acpi/cppc_acpi.c > +++ b/drivers/acpi/cppc_acpi.c > @@ -119,23 +119,15 @@ static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr); > */ > #define NUM_RETRIES 500ULL > > -struct cppc_attr { > - struct attribute attr; > - ssize_t (*show)(struct kobject *kobj, > - struct attribute *attr, char *buf); > - ssize_t (*store)(struct kobject *kobj, > - struct attribute *attr, const char *c, ssize_t count); > -}; > - > #define define_one_cppc_ro(_name) \ > -static struct cppc_attr _name = \ > +static struct kobj_attribute _name = \ > __ATTR(_name, 0444, show_##_name, NULL) > > #define to_cpc_desc(a) container_of(a, struct cpc_desc, kobj) > > #define show_cppc_data(access_fn, struct_name, member_name) \ > static ssize_t show_##member_name(struct kobject *kobj, \ > - struct attribute *attr, char *buf) \ > + struct kobj_attribute *attr, char *buf) \ > { \ > struct cpc_desc *cpc_ptr = to_cpc_desc(kobj); \ > struct struct_name st_name = {0}; \ > @@ -161,7 +153,7 @@ show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, reference_perf); > show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, wraparound_time); > > static ssize_t show_feedback_ctrs(struct kobject *kobj, > - struct attribute *attr, char *buf) > + struct kobj_attribute *attr, char *buf) > { > struct cpc_desc *cpc_ptr = to_cpc_desc(kobj); > struct cppc_perf_fb_ctrs fb_ctrs = {0}; > > base-commit: 454859c552da78b0f587205d308401922b56863e > -- Applied as 5.13 material, thanks!
