[PATCH 3.16 060/294] kprobes/x86: Release insn_slot in failure path

From: Ben Hutchings
Date: Mon Nov 06 2017 - 19:18:24 EST


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

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

From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>

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@xxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
Cc: David S . Miller <davem@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
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)