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Wed, 27 Aug 2025 19:50:25 -0700 (PDT) Message-ID: <8ed15a17-618f-4277-afc3-934939292060@kernel.dk> Date: Wed, 27 Aug 2025 20:50:24 -0600 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] io_uring/kbuf: fix infinite loop in io_kbuf_inc_commit() To: Qingyue Zhang Cc: aftern00n@qq.com, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <8abaf4ad-d457-422d-9e9e-932cab2588e6@kernel.dk> Content-Language: en-US From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/27/25 8:49 PM, Qingyue Zhang wrote: > On Wed, 27 Aug 2025 20:08:05 -0600, Jens Axboe wrote: >> I don't think there's anything wrong with the looping and stopping at >> the other end is of course a safe guard, but couldn't we just abort the >> loop if we see a 0 sized buffer? At that point we know the buffer is >> invalid, or the kernel is buggy, and it'd be saner to stop at that >> point. Something ala: >> >> >> diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c >> index 394037d3f2f6..19a8bde5e1e1 100644 >> --- a/io_uring/kbuf.c >> +++ b/io_uring/kbuf.c >> @@ -42,7 +42,8 @@ static bool io_kbuf_inc_commit(struct io_buffer_list *bl, int len) >> buf_len = READ_ONCE(buf->len); >> this_len = min_t(u32, len, buf_len); >> buf_len -= this_len; >> - if (buf_len) { >> + /* Stop looping for invalid buffer length of 0 */ >> + if (buf_len || !this_len) { >> buf->addr += this_len; >> buf->len = buf_len; >> return false; > > Good idea, it looks nice to me. I'll send it out, I amended the commit message a bit too. -- Jens Axboe