linux-kernel - [PATCH 1/2] x86/events/amd/iommu: Fix sysfs type mismatch

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Message-Id: <20210415001112.3024673-1-nathan@kernel.org>
Date:   Wed, 14 Apr 2021 17:11:11 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Kees Cook <keescook@...omium.org>
Cc:     Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com,
        Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH 1/2] x86/events/amd/iommu: Fix sysfs type mismatch

dev_attr_show() calls _iommu_event_show() via an indirect call but
_iommu_event_show()'s type does not currently match the type of the
show() member in 'struct device_attribute', resulting in a Control Flow
Integrity violation.

$ cat /sys/devices/amd_iommu_1/events/mem_dte_hit
csource=0x0a

$ dmesg | grep "CFI failure"
[ 3526.735140] CFI failure (target: _iommu_event_show...):

Change _iommu_event_show() and 'struct amd_iommu_event_desc' to
'struct device_attribute' so that there is no more CFI violation.

Link: https://github.com/ClangBuiltLinux/linux/issues/1350
Fixes: 7be6296fdd75 ("perf/x86/amd: AMD IOMMU Performance Counter PERF uncore PMU implementation")
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 arch/x86/events/amd/iommu.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
index be50ef8572cc..6a98a7651621 100644
--- a/arch/x86/events/amd/iommu.c
+++ b/arch/x86/events/amd/iommu.c
@@ -81,12 +81,12 @@ static struct attribute_group amd_iommu_events_group = {
 };
 
 struct amd_iommu_event_desc {
-	struct kobj_attribute attr;
+	struct device_attribute attr;
 	const char *event;
 };
 
-static ssize_t _iommu_event_show(struct kobject *kobj,
-				struct kobj_attribute *attr, char *buf)
+static ssize_t _iommu_event_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
 {
 	struct amd_iommu_event_desc *event =
 		container_of(attr, struct amd_iommu_event_desc, attr);

base-commit: d434405aaab7d0ebc516b68a8fc4100922d7f5ef
-- 
2.31.1.272.g89b43f80a5