linux-kernel - [PATCH 3.16 060/294] kprobes/x86: Release insn

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Date:   Mon, 06 Nov 2017 23:03:02 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Thomas Gleixner" <tglx@...utronix.de>,
        "Anil S Keshavamurthy" <anil.s.keshavamurthy@...el.com>,
        "Ingo Molnar" <mingo@...nel.org>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Masami Hiramatsu" <mhiramat@...nel.org>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Ananth N Mavinakayanahalli" <ananth@...ibm.com>,
        "David S . Miller" <davem@...emloft.net>
Subject: [PATCH 3.16 060/294] kprobes/x86: Release insn_slot in failure path

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Masami Hiramatsu <mhiramat@...nel.org>

commit 38115f2f8cec8087d558c062e779c443a01f87d6 upstream.

The following commit:

  003002e04ed3 ("kprobes: Fix arch_prepare_kprobe to handle copy insn failures")

returns an error if the copying of the instruction, but does not release
the allocated insn_slot.

Clean up correctly.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>
Cc: David S . Miller <davem@...emloft.net>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Fixes: 003002e04ed3 ("kprobes: Fix arch_prepare_kprobe to handle copy insn failures")
Link: http://lkml.kernel.org/r/150064834183.6172.11694375818447664416.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/kernel/kprobes/core.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -401,6 +401,8 @@ static int arch_copy_kprobe(struct kprob
 
 int arch_prepare_kprobe(struct kprobe *p)
 {
+	int ret;
+
 	if (alternatives_text_reserved(p->addr, p->addr))
 		return -EINVAL;
 
@@ -411,7 +413,13 @@ int arch_prepare_kprobe(struct kprobe *p
 	if (!p->ainsn.insn)
 		return -ENOMEM;
 
-	return arch_copy_kprobe(p);
+	ret = arch_copy_kprobe(p);
+	if (ret) {
+		free_insn_slot(p->ainsn.insn, 0);
+		p->ainsn.insn = NULL;
+	}
+
+	return ret;
 }
 
 void arch_arm_kprobe(struct kprobe *p)