From de2ce6b14bc3e565708a39bdba3ef9162aeffc72 Mon Sep 17 00:00:00 2001 From: Noorain Eqbal Date: Mon, 20 Oct 2025 23:33:01 +0530 Subject: [PATCH] bpf: Sync pending IRQ work before freeing ring buffer [ Upstream commit 4e9077638301816a7d73fa1e1b4c1db4a7e3b59c ] Fix a race where irq_work can be queued in bpf_ringbuf_commit() but the ring buffer is freed before the work executes. In the syzbot reproducer, a BPF program attached to sched_switch triggers bpf_ringbuf_commit(), queuing an irq_work. If the ring buffer is freed before this work executes, the irq_work thread may accesses freed memory. Calling `irq_work_sync(&rb->work)` ensures that all pending irq_work complete before freeing the buffer. Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") Reported-by: syzbot+2617fc732430968b45d2@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=2617fc732430968b45d2 Tested-by: syzbot+2617fc732430968b45d2@syzkaller.appspotmail.com Signed-off-by: Noorain Eqbal Link: https://lore.kernel.org/r/20251020180301.103366-1-nooraineqbal@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/ringbuf.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c index eb6ff0d0c06b..a8b8f023ff79 100644 --- a/kernel/bpf/ringbuf.c +++ b/kernel/bpf/ringbuf.c @@ -190,6 +190,8 @@ static void bpf_ringbuf_free(struct bpf_ringbuf *rb) struct page **pages = rb->pages; int i, nr_pages = rb->nr_pages; + irq_work_sync(&rb->work); + vunmap(rb); for (i = 0; i < nr_pages; i++) __free_page(pages[i]);