linux-kernel - [PATCH] jprobes: Ensure that the probepoint is at function entry

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Message-Id: <20170629145655.5282-1-naveen.n.rao@linux.vnet.ibm.com>
Date:   Thu, 29 Jun 2017 20:26:55 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>,
        Ingo Molnar <mingo@...nel.org>
Cc:     Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] jprobes: Ensure that the probepoint is at function entry

Similar to commit 90ec5e89e393c ("kretprobes: Ensure probe location is
at function entry"), ensure that the jprobe probepoint is at function
entry.

Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
---
 kernel/kprobes.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index adfe3b4cfe05..950018609339 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1776,9 +1776,14 @@ int register_jprobes(struct jprobe **jps, int num)
 		jp = jps[i];
 		addr = arch_deref_entry_point(jp->entry);
 
-		/* Verify probepoint is a function entry point */
+		/*
+		 * Verify probepoint as well as the jprobe handler are
+		 * function entry points.
+		 */
 		if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
-		    offset == 0) {
+				offset == 0 &&
+				function_offset_within_entry(jp->kp.addr,
+					jp->kp.symbol_name, jp->kp.offset)) {
 			jp->kp.pre_handler = setjmp_pre_handler;
 			jp->kp.break_handler = longjmp_break_handler;
 			ret = register_kprobe(&jp->kp);
-- 
2.13.1