From: Nathan Chancellor natechancellor@gmail.com
commit e6d701dca9893990d999fd145e3e07223c002b06 upstream.
When running a kernel with Clang's Control Flow Integrity implemented, there is a violation that happens when accessing /sys/firmware/acpi/pm_profile:
$ cat /sys/firmware/acpi/pm_profile 0
$ dmesg ... [ 17.352564] ------------[ cut here ]------------ [ 17.352568] CFI failure (target: acpi_show_profile+0x0/0x8): [ 17.352572] WARNING: CPU: 3 PID: 497 at kernel/cfi.c:29 __cfi_check_fail+0x33/0x40 [ 17.352573] Modules linked in: [ 17.352575] CPU: 3 PID: 497 Comm: cat Tainted: G W 5.7.0-microsoft-standard+ #1 [ 17.352576] RIP: 0010:__cfi_check_fail+0x33/0x40 [ 17.352577] Code: 48 c7 c7 50 b3 85 84 48 c7 c6 50 0a 4e 84 e8 a4 d8 60 00 85 c0 75 02 5b c3 48 c7 c7 dc 5e 49 84 48 89 de 31 c0 e8 7d 06 eb ff <0f> 0b 5b c3 00 00 cc cc 00 00 cc cc 00 85 f6 74 25 41 b9 ea ff ff [ 17.352577] RSP: 0018:ffffaa6dc3c53d30 EFLAGS: 00010246 [ 17.352578] RAX: 331267e0c06cee00 RBX: ffffffff83d85890 RCX: ffffffff8483a6f8 [ 17.352579] RDX: ffff9cceabbb37c0 RSI: 0000000000000082 RDI: ffffffff84bb9e1c [ 17.352579] RBP: ffffffff845b2bc8 R08: 0000000000000001 R09: ffff9cceabbba200 [ 17.352579] R10: 000000000000019d R11: 0000000000000000 R12: ffff9cc947766f00 [ 17.352580] R13: ffffffff83d6bd50 R14: ffff9ccc6fa80000 R15: ffffffff845bd328 [ 17.352582] FS: 00007fdbc8d13580(0000) GS:ffff9cce91ac0000(0000) knlGS:0000000000000000 [ 17.352582] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 17.352583] CR2: 00007fdbc858e000 CR3: 00000005174d0000 CR4: 0000000000340ea0 [ 17.352584] Call Trace: [ 17.352586] ? rev_id_show+0x8/0x8 [ 17.352587] ? __cfi_check+0x45bac/0x4b640 [ 17.352589] ? kobj_attr_show+0x73/0x80 [ 17.352590] ? sysfs_kf_seq_show+0xc1/0x140 [ 17.352592] ? ext4_seq_options_show.cfi_jt+0x8/0x8 [ 17.352593] ? seq_read+0x180/0x600 [ 17.352595] ? sysfs_create_file_ns.cfi_jt+0x10/0x10 [ 17.352596] ? tlbflush_read_file+0x8/0x8 [ 17.352597] ? __vfs_read+0x6b/0x220 [ 17.352598] ? handle_mm_fault+0xa23/0x11b0 [ 17.352599] ? vfs_read+0xa2/0x130 [ 17.352599] ? ksys_read+0x6a/0xd0 [ 17.352601] ? __do_sys_getpgrp+0x8/0x8 [ 17.352602] ? do_syscall_64+0x72/0x120 [ 17.352603] ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 17.352604] ---[ end trace 7b1fa81dc897e419 ]---
When /sys/firmware/acpi/pm_profile is read, sysfs_kf_seq_show is called, which in turn calls kobj_attr_show, which gets the ->show callback member by calling container_of on attr (casting it to struct kobj_attribute) then calls it.
There is a CFI violation because pm_profile_attr is of type struct device_attribute but kobj_attr_show calls ->show expecting it to be from struct kobj_attribute. CFI checking ensures that function pointer types match when doing indirect calls. Fix pm_profile_attr to be defined in terms of kobj_attribute so there is no violation or mismatch.
Fixes: 362b646062b2 ("ACPI: Export FADT pm_profile integer value to userspace") Link: https://github.com/ClangBuiltLinux/linux/issues/1051 Reported-by: yuu ichii byahu140@heisei.be Signed-off-by: Nathan Chancellor natechancellor@gmail.com Cc: 3.10+ stable@vger.kernel.org # 3.10+ Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/acpi/sysfs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c index 3a89909b50a6c..76c668c05fa03 100644 --- a/drivers/acpi/sysfs.c +++ b/drivers/acpi/sysfs.c @@ -938,13 +938,13 @@ static void __exit interrupt_stats_exit(void) }
static ssize_t -acpi_show_profile(struct device *dev, struct device_attribute *attr, +acpi_show_profile(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sprintf(buf, "%d\n", acpi_gbl_FADT.preferred_profile); }
-static const struct device_attribute pm_profile_attr = +static const struct kobj_attribute pm_profile_attr = __ATTR(pm_profile, S_IRUGO, acpi_show_profile, NULL);
static ssize_t hotplug_enabled_show(struct kobject *kobj,