linux-kernel - [PATCH] bpf: sync pending IRQ work before freeing ring buffer

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Message-ID: <20251018181156.59907-1-nooraineqbal@gmail.com>
Date: Sat, 18 Oct 2025 23:41:56 +0530
From: neqbal <nooraineqbal@...il.com>
To: ast@...nel.org,
	andrii@...nel.org
Cc: daniel@...earbox.net,
	martin.lau@...ux.dev,
	eddyz87@...il.com,
	song@...nel.org,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	sdf@...ichev.me,
	haoluo@...gle.com,
	jolsa@...nel.org,
	bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	skhan@...uxfoundation.org,
	david.hunter@...uxfoundation.org,
	syzbot+2617fc732430968b45d2@...kaller.appspotmail.com,
	linux-kernel-mentees@...ts.linux.dev,
	neqbal <nooraineqbal@...il.com>
Subject: [PATCH] bpf: sync pending IRQ work before freeing ring buffer

Fix a possible vmalloc out-of-bounds access caused by pending IRQ work
by ensuring all pending IRQ work completes before freeing.

Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Reported-by: syzbot+2617fc732430968b45d2@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=2617fc732430968b45d2
Tested-by: syzbot+2617fc732430968b45d2@...kaller.appspotmail.com
Signed-off-by: neqbal <nooraineqbal@...il.com>
---
 kernel/bpf/ringbuf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index 719d73299397..d706c4b7f532 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -216,6 +216,8 @@ static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr)
 
 static void bpf_ringbuf_free(struct bpf_ringbuf *rb)
 {
+	irq_work_sync(&rb->work);
+
 	/* copy pages pointer and nr_pages to local variable, as we are going
 	 * to unmap rb itself with vunmap() below
 	 */
-- 
2.51.0