[PATCH 1/1] io_uring/zctx: check chained notif contexts

[PATCH 1/1] io_uring/zctx: check chained notif contexts

[Pavel Begunkov]

Send zc only links ubuf_info for requests coming from the same context.
There are some ambiguous syz reports, so let's check the assumption on
notification completion.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/notif.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/io_uring/notif.c b/io_uring/notif.c
index 9a6f6e92d742..8c92e9cde2c6 100644
--- a/io_uring/notif.c
+++ b/io_uring/notif.c
@@ -14,10 +14,15 @@ static const struct ubuf_info_ops io_ubuf_ops;
 static void io_notif_tw_complete(struct io_kiocb *notif, io_tw_token_t tw)
 {
 	struct io_notif_data *nd = io_notif_to_data(notif);
+	struct io_ring_ctx *ctx = notif->ctx;
+
+	lockdep_assert_held(&ctx->uring_lock);
 
 	do {
 		notif = cmd_to_io_kiocb(nd);
 
+		if (WARN_ON_ONCE(ctx != notif->ctx))
+			return;
 		lockdep_assert(refcount_read(&nd->uarg.refcnt) == 0);
 
 		if (unlikely(nd->zc_report) && (nd->zc_copied || !nd->zc_used))
-- 
2.49.0

Re: [PATCH 1/1] io_uring/zctx: check chained notif contexts

[Pavel Begunkov]

On 8/14/25 15:40, Pavel Begunkov wrote:
> Send zc only links ubuf_info for requests coming from the same context.
> There are some ambiguous syz reports, so let's check the assumption on
> notification completion.

This one would be great to have to hopefully start tackling
the syzbot report.


> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>   io_uring/notif.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/io_uring/notif.c b/io_uring/notif.c
> index 9a6f6e92d742..8c92e9cde2c6 100644
> --- a/io_uring/notif.c
> +++ b/io_uring/notif.c
> @@ -14,10 +14,15 @@ static const struct ubuf_info_ops io_ubuf_ops;
>   static void io_notif_tw_complete(struct io_kiocb *notif, io_tw_token_t tw)
>   {
>   	struct io_notif_data *nd = io_notif_to_data(notif);
> +	struct io_ring_ctx *ctx = notif->ctx;
> +
> +	lockdep_assert_held(&ctx->uring_lock);
>   
>   	do {
>   		notif = cmd_to_io_kiocb(nd);
>   
> +		if (WARN_ON_ONCE(ctx != notif->ctx))
> +			return;
>   		lockdep_assert(refcount_read(&nd->uarg.refcnt) == 0);
>   
>   		if (unlikely(nd->zc_report) && (nd->zc_copied || !nd->zc_used))

-- 
Pavel Begunkov

Re: [PATCH 1/1] io_uring/zctx: check chained notif contexts

[Jens Axboe]

On Thu, 14 Aug 2025 15:40:57 +0100, Pavel Begunkov wrote:
> Send zc only links ubuf_info for requests coming from the same context.
> There are some ambiguous syz reports, so let's check the assumption on
> notification completion.
> 
> 

Applied, thanks!

[1/1] io_uring/zctx: check chained notif contexts
      commit: aad1370a6125e1f676c18aabc2e819348e65c25a

Best regards,
-- 
Jens Axboe