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@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240929144230.GA9468@redhat.com

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 5106dc181387282ba23e496aac3cee74f76f6f9a..15e91a38d327f279637573db72e9a27078efd6d7 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1905,18 +1905,14 @@ 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",
@@ -1977,14 +1973,10 @@ fail:
 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;