linux-kernel - [PATCH 4.19 174/287] kprobes: Forbid probing on trampoline and BPF code areas

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Message-Id: <20220823080106.619249065@linuxfoundation.org>
Date:   Tue, 23 Aug 2022 10:25:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chen Zhongjin <chenzhongjin@...wei.com>,
        Ingo Molnar <mingo@...nel.org>,
        "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 174/287] kprobes: Forbid probing on trampoline and BPF code areas

From: Chen Zhongjin <chenzhongjin@...wei.com>

[ Upstream commit 28f6c37a2910f565b4f5960df52b2eccae28c891 ]

kernel_text_address() treats ftrace_trampoline, kprobe_insn_slot
and bpf_text_address as valid kprobe addresses - which is not ideal.

These text areas are removable and changeable without any notification
to kprobes, and probing on them can trigger unexpected behavior:

  https://lkml.org/lkml/2022/7/26/1148

Considering that jump_label and static_call text are already
forbiden to probe, kernel_text_address() should be replaced with
core_kernel_text() and is_module_text_address() to check other text
areas which are unsafe to kprobe.

[ mingo: Rewrote the changelog. ]

Fixes: 5b485629ba0d ("kprobes, extable: Identify kprobes trampolines as kernel text area")
Fixes: 74451e66d516 ("bpf: make jited programs visible in traces")
Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Link: https://lore.kernel.org/r/20220801033719.228248-1-chenzhongjin@huawei.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/kprobes.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 993b84cc1db5..099191716d4c 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1566,7 +1566,8 @@ static int check_kprobe_address_safe(struct kprobe *p,
 	preempt_disable();
 
 	/* Ensure it is not in reserved area nor out of text */
-	if (!kernel_text_address((unsigned long) p->addr) ||
+	if (!(core_kernel_text((unsigned long) p->addr) ||
+	    is_module_text_address((unsigned long) p->addr)) ||
 	    within_kprobe_blacklist((unsigned long) p->addr) ||
 	    jump_label_text_reserved(p->addr, p->addr) ||
 	    find_bug((unsigned long)p->addr)) {
-- 
2.35.1