linux-kernel - [PATCH 1/7] uprobes: don't abuse get_utask() in pre_ssout() and prepare

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Message-ID: <20240929144230.GA9468@redhat.com>
Date: Sun, 29 Sep 2024 16:42:30 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Andrii Nakryiko <andrii@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc: Liao Chang <liaochang1@...wei.com>, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Subject: [PATCH 1/7] uprobes: don't abuse get_utask() in pre_ssout() and
 prepare_uretprobe()

handle_swbp() calls get_utask() before prepare_uretprobe() or pre_ssout()
can be called, they can simply use current->utask which can't be NULL.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 4b52cb2ae6d6..2a9cdd5c82d7 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1908,18 +1908,14 @@ static void cleanup_return_instances(struct uprobe_task *utask, bool chained,
 
 static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
 {
-	struct return_instance *ri;
-	struct uprobe_task *utask;
+	struct uprobe_task *utask = current->utask;
 	unsigned long orig_ret_vaddr, trampoline_vaddr;
+	struct return_instance *ri;
 	bool chained;
 
 	if (!get_xol_area())
 		return;
 
-	utask = get_utask();
-	if (!utask)
-		return;
-
 	if (utask->depth >= MAX_URETPROBE_DEPTH) {
 		printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to"
 				" nestedness limit pid/tgid=%d/%d\n",
@@ -1980,14 +1976,10 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
 static int
 pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
 {
-	struct uprobe_task *utask;
+	struct uprobe_task *utask = current->utask;
 	unsigned long xol_vaddr;
 	int err;
 
-	utask = get_utask();
-	if (!utask)
-		return -ENOMEM;
-
 	if (!try_get_uprobe(uprobe))
 		return -EINVAL;
 
-- 
2.25.1.362.g51ebf55