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Tue, 20 Jul 2021 03:17:11 -0700 (PDT) Subject: Re: [PATCH] io_uring: fix memleak in io_init_wq_offload() To: Yang Yingliang , linux-kernel@vger.kernel.org, io-uring@vger.kernel.org Cc: axboe@kernel.dk References: <20210720083805.3030730-1-yangyingliang@huawei.com> From: Pavel Begunkov Message-ID: <990880a3-2f0f-3b2c-88e8-a626032b44df@gmail.com> Date: Tue, 20 Jul 2021 11:16:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210720083805.3030730-1-yangyingliang@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/20/21 9:38 AM, Yang Yingliang wrote: > I got memory leak report when doing fuzz test: Reviewed-by: Pavel Begunkov Cc: stable@vger.kernel.org > > BUG: memory leak > unreferenced object 0xffff888107310a80 (size 96): > comm "syz-executor.6", pid 4610, jiffies 4295140240 (age 20.135s) > hex dump (first 32 bytes): > 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... > backtrace: > [<000000001974933b>] kmalloc include/linux/slab.h:591 [inline] > [<000000001974933b>] kzalloc include/linux/slab.h:721 [inline] > [<000000001974933b>] io_init_wq_offload fs/io_uring.c:7920 [inline] > [<000000001974933b>] io_uring_alloc_task_context+0x466/0x640 fs/io_uring.c:7955 > [<0000000039d0800d>] __io_uring_add_tctx_node+0x256/0x360 fs/io_uring.c:9016 > [<000000008482e78c>] io_uring_add_tctx_node fs/io_uring.c:9052 [inline] > [<000000008482e78c>] __do_sys_io_uring_enter fs/io_uring.c:9354 [inline] > [<000000008482e78c>] __se_sys_io_uring_enter fs/io_uring.c:9301 [inline] > [<000000008482e78c>] __x64_sys_io_uring_enter+0xabc/0xc20 fs/io_uring.c:9301 > [<00000000b875f18f>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] > [<00000000b875f18f>] do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80 > [<000000006b0a8484>] entry_SYSCALL_64_after_hwframe+0x44/0xae > > CPU0 CPU1 > io_uring_enter io_uring_enter > io_uring_add_tctx_node io_uring_add_tctx_node > __io_uring_add_tctx_node __io_uring_add_tctx_node > io_uring_alloc_task_context io_uring_alloc_task_context > io_init_wq_offload io_init_wq_offload > hash = kzalloc hash = kzalloc > ctx->hash_map = hash ctx->hash_map = hash <- one of the hash is leaked > > When calling io_uring_enter() in parallel, the 'hash_map' will be leaked, > add uring_lock to protect 'hash_map'. > > Fixes: e941894eae31 ("io-wq: make buffered file write hashed work map per-ctx") > Reported-by: Hulk Robot > Signed-off-by: Yang Yingliang > --- > fs/io_uring.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 0cac361bf6b8..63d3a9c2a2a6 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -7899,15 +7899,19 @@ static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx, > struct io_wq_data data; > unsigned int concurrency; > > + mutex_lock(&ctx->uring_lock); > hash = ctx->hash_map; > if (!hash) { > hash = kzalloc(sizeof(*hash), GFP_KERNEL); > - if (!hash) > + if (!hash) { > + mutex_unlock(&ctx->uring_lock); > return ERR_PTR(-ENOMEM); > + } > refcount_set(&hash->refs, 1); > init_waitqueue_head(&hash->wait); > ctx->hash_map = hash; > } > + mutex_unlock(&ctx->uring_lock); > > data.hash = hash; > data.task = task; > -- Pavel Begunkov