[PATCH 1/7] uprobes: don't abuse get_utask() in pre_ssout() and prepare_uretprobe()

From: Oleg Nesterov
Date: Sun Sep 29 2024 - 10:43:00 EST


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@xxxxxxxxxx>
---
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