linux-kernel - [PATCH 07/13] powerpc/kprobes: Unpoison instruction in kprobe struct

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Message-Id: <20231214055539.9420-8-nicholas@linux.ibm.com>
Date:   Thu, 14 Dec 2023 05:55:33 +0000
From:   Nicholas Miehlbradt <nicholas@...ux.ibm.com>
To:     glider@...gle.com, elver@...gle.com, dvyukov@...gle.com,
        akpm@...ux-foundation.org, mpe@...erman.id.au, npiggin@...il.com,
        christophe.leroy@...roup.eu
Cc:     linux-mm@...ck.org, kasan-dev@...glegroups.com, iii@...ux.ibm.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Nicholas Miehlbradt <nicholas@...ux.ibm.com>
Subject: [PATCH 07/13] powerpc/kprobes: Unpoison instruction in kprobe struct

KMSAN does not unpoison the ainsn field of a kprobe struct correctly.
Manually unpoison it to prevent false positives.

Signed-off-by: Nicholas Miehlbradt <nicholas@...ux.ibm.com>
---
 arch/powerpc/kernel/kprobes.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index b20ee72e873a..1cbec54f2b6a 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -27,6 +27,7 @@
 #include <asm/sections.h>
 #include <asm/inst.h>
 #include <linux/uaccess.h>
+#include <linux/kmsan-checks.h>
 
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
@@ -179,6 +180,7 @@ int arch_prepare_kprobe(struct kprobe *p)
 
 	if (!ret) {
 		patch_instruction(p->ainsn.insn, insn);
+		kmsan_unpoison_memory(p->ainsn.insn, sizeof(kprobe_opcode_t));
 		p->opcode = ppc_inst_val(insn);
 	}
 
-- 
2.40.1