From: Nathan Chancellor nathan@kernel.org
[ Upstream commit 2bc6262c6117dd18106d5aa50d53e945b5d99c51 ]
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 difference 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@google.com/
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@kernel.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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};