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([2620:10d:c092:600::1:eaba]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488c1c5291esm150797065e9.15.2026.04.08.01.34.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Apr 2026 01:34:56 -0700 (PDT) Message-ID: <336062ec-5fcd-46ad-a839-6ddbff7f9fb9@gmail.com> Date: Wed, 8 Apr 2026 09:34:59 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] io_uring: fix pinned pages and pages array leak in io_region_pin_pages() To: KobaK , Jens Axboe Cc: Keith Busch , Ming Lei , io-uring@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260408065408.2017967-1-kobak@nvidia.com> <20260408065408.2017967-2-kobak@nvidia.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20260408065408.2017967-2-kobak@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 4/8/26 07:54, KobaK wrote: > From: Koba Ko > > When io_pin_pages() succeeds but the subsequent nr_pages sanity check > fires (WARN_ON_ONCE), the function returns -EFAULT without unpinning the > user pages or freeing the kvmalloc'd pages array. The caller's cleanup > via io_free_region() won't help either, because mr->pages was never > assigned — so the entire cleanup block is skipped. > > Add unpin_user_pages() and kvfree() before the error return to prevent > the leak. > > Fixes: a90558b36ccee ("io_uring/memmap: helper for pinning region pages") > Signed-off-by: Koba Ko It's a WARN path, it should never happen, but if it does, that means io_pin_pages() is buggy, and it's better to leak rather than risk something nastier. > --- > io_uring/memmap.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/io_uring/memmap.c b/io_uring/memmap.c > index e6958968975a8..9f0d3750ce3bc 100644 > --- a/io_uring/memmap.c > +++ b/io_uring/memmap.c > @@ -141,8 +141,11 @@ static int io_region_pin_pages(struct io_mapped_region *mr, > pages = io_pin_pages(reg->user_addr, size, &nr_pages); > if (IS_ERR(pages)) > return PTR_ERR(pages); > - if (WARN_ON_ONCE(nr_pages != mr->nr_pages)) > + if (WARN_ON_ONCE(nr_pages != mr->nr_pages)) { > + unpin_user_pages(pages, nr_pages); > + kvfree(pages); > return -EFAULT; > + } > > mr->pages = pages; > mr->flags |= IO_REGION_F_USER_PROVIDED; -- Pavel Begunkov