From 3ecd3e03144b38a21a3b70254f1b9d2e16629b09 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 19 Mar 2026 14:29:09 -0600 Subject: [PATCH] io_uring/kbuf: fix missing BUF_MORE for incremental buffers at EOF For a zero length transfer, io_kbuf_inc_commit() is called with !len. Since we never enter the while loop to consume the buffers, io_kbuf_inc_commit() ends up returning true, consuming the buffer. But if no data was consumed, by definition it cannot have consumed the buffer. Return false for that case. Reported-by: Martin Michaelis Cc: stable@vger.kernel.org Fixes: ae98dbf43d75 ("io_uring/kbuf: add support for incremental buffer consumption") Link: https://github.com/axboe/liburing/issues/1553 Signed-off-by: Jens Axboe --- io_uring/kbuf.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c index e7f444953dfb..a4cb6752b7aa 100644 --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -34,6 +34,10 @@ struct io_provide_buf { static bool io_kbuf_inc_commit(struct io_buffer_list *bl, int len) { + /* No data consumed, return false early to avoid consuming the buffer */ + if (!len) + return false; + while (len) { struct io_uring_buf *buf; u32 buf_len, this_len;