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From: Masami Hiramatsu <mhiramat@kernel.org>
To: x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	Steven Rostedt <rostedt@goodmis.org>,
	Francis Deslauriers <francis.deslauriers@efficios.com>,
	Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
	Borislav Petkov <bp@suse.de>, Yonghong Song <yhs@fb.com>
Subject: [PATCH 2/2] uprobes: x86: Prohibit probing on MOV SS instruction
Date: Wed,  9 May 2018 21:58:45 +0900	[thread overview]
Message-ID: <152587072544.17316.5950935243917346341.stgit@devbox> (raw)
In-Reply-To: <152587066475.17316.3035446966107675608.stgit@devbox>

Since MOV SS and POP SS instructions will delay the exceptions
until the next instruction is executed, we should not do
single-stepping on it by uprobes.

uprobe already rejects probing on POP SS (0x1f), but allows
probing on MOV SS (0x8e and reg == 2).
This checks the target instruction and if it is MOV SS
or POP SS, returns -ENOTSUPP to reject probing.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 arch/x86/kernel/uprobes.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 85c7ef23d99f..c84bb5396958 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -299,6 +299,10 @@ static int uprobe_init_insn(struct arch_uprobe *auprobe, struct insn *insn, bool
 	if (is_prefix_bad(insn))
 		return -ENOTSUPP;
 
+	/* We should not singlestep on the exception masking instructions */
+	if (insn_masking_exception(insn))
+		return -ENOTSUPP;
+
 	if (x86_64)
 		good_insns = good_insns_64;
 	else

  parent reply	other threads:[~2018-05-09 12:59 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-09 12:57 [PATCH 0/2] uprobes: x86: Reject probing MOV SS Masami Hiramatsu
2018-05-09 12:58 ` [PATCH 1/2] kprobes: x86: Prohibit probing on exception masking instructions Masami Hiramatsu
2018-05-13 17:57   ` [tip:x86/urgent] kprobes/x86: " tip-bot for Masami Hiramatsu
2018-05-09 12:58 ` Masami Hiramatsu [this message]
2018-05-09 16:39   ` [PATCH 2/2] uprobes: x86: Prohibit probing on MOV SS instruction Oleg Nesterov
2018-05-13 17:58   ` [tip:x86/urgent] uprobes/x86: " tip-bot for Masami Hiramatsu
2018-05-09 13:01 ` [PATCH 0/2] uprobes: kprobes: x86: Reject probing MOV SS/POP SS Masami Hiramatsu
2018-05-09 14:36 ` [PATCH 0/2] uprobes: x86: Reject probing MOV SS Andy Lutomirski
2018-05-09 22:25   ` Masami Hiramatsu

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