2024-02-24 10:31:37

by linke li

[permalink] [raw]
Subject: [PATCH] uprobes: use READ_ONCE() to read mm->uprobes_state.xol_area in concurrent environment

In function get_xol_area(), mm->uprobes_state.xol_area is read using
READ_ONCE() in line 1534

1534 area = READ_ONCE(mm->uprobes_state.xol_area); /* ^^^ */

while read directly in line 1530

1530 if (!mm->uprobes_state.xol_area)
1531 __create_xol_area(0);

In the same environment, reads in two places should have the same
protection.

Signed-off-by: linke li <[email protected]>
---
kernel/events/uprobes.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 929e98c62965..e110941fbc6b 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1527,7 +1527,7 @@ static struct xol_area *get_xol_area(void)
struct mm_struct *mm = current->mm;
struct xol_area *area;

- if (!mm->uprobes_state.xol_area)
+ if (!READ_ONCE(mm->uprobes_state.xol_area))
__create_xol_area(0);

/* Pairs with xol_add_vma() smp_store_release() */
--
2.39.3 (Apple Git-145)