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Date:   Fri, 13 Jan 2023 10:41:01 -0800
From:   Kees Cook <keescook@chromium.org>
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     Yupeng Li <liyupeng@zbhlos.com>, tariqt@nvidia.com,
        davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, netdev@vger.kernel.org,
        linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        Caicai <caizp2008@163.com>
Subject: Re: [PATCH 1/1] net/mlx4: Fix build error use array_size() helper in
 copy_to_user()
Message-ID: <202301131039.7354AD35CF@keescook>
References: <20230107072725.673064-1-liyupeng@zbhlos.com>
 <Y7wb1hCpJiGEdbav@ziepe.ca>
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On Mon, Jan 09, 2023 at 09:51:18AM -0400, Jason Gunthorpe wrote:
> On Sat, Jan 07, 2023 at 03:27:25PM +0800, Yupeng Li wrote:
> > When CONFIG_64BIT was disabled, check_copy_size() was declared with
> > attribute error: copy source size is too small, array_size() for 32BIT
> > was wrong size, some compiled msg with error like:
> > 
> >   CALL    scripts/checksyscalls.sh
> >   CC [M]  drivers/net/ethernet/mellanox/mlx4/cq.o
> > In file included from ./arch/x86/include/asm/preempt.h:7,
> >                  from ./include/linux/preempt.h:78,
> >                  from ./include/linux/percpu.h:6,
> >                  from ./include/linux/context_tracking_state.h:5,
> >                  from ./include/linux/hardirq.h:5,
> >                  from drivers/net/ethernet/mellanox/mlx4/cq.c:37:
> > In function ‘check_copy_size’,
> >     inlined from ‘copy_to_user’ at ./include/linux/uaccess.h:168:6,
> >     inlined from ‘mlx4_init_user_cqes’ at drivers/net/ethernet/mellanox/mlx4/cq.c:317:9,
> >     inlined from ‘mlx4_cq_alloc’ at drivers/net/ethernet/mellanox/mlx4/cq.c:394:10:
> > ./include/linux/thread_info.h:228:4: error: call to ‘__bad_copy_from’ declared with attribute error: copy source size is too small
> >   228 |    __bad_copy_from();
> >       |    ^~~~~~~~~~~~~~~~~
> > make[6]: *** [scripts/Makefile.build:250：drivers/net/ethernet/mellanox/mlx4/cq.o] 错误 1
> > make[5]: *** [scripts/Makefile.build:500：drivers/net/ethernet/mellanox/mlx4] 错误 2
> > make[5]: *** 正在等待未完成的任务....
> > make[4]: *** [scripts/Makefile.build:500：drivers/net/ethernet/mellanox] 错误 2
> > make[3]: *** [scripts/Makefile.build:500：drivers/net/ethernet] 错误 2
> > make[3]: *** 正在等待未完成的任务....
> > make[2]: *** [scripts/Makefile.build:500：drivers/net] 错误 2
> > make[2]: *** 正在等待未完成的任务....
> > make[1]: *** [scripts/Makefile.build:500：drivers] 错误 2
> > make: *** [Makefile:1992：.] 错误 2
> > 
> > Signed-off-by: Yupeng Li <liyupeng@zbhlos.com>
> > Reviewed-by: Caicai <caizp2008@163.com>
> > ---
> >  drivers/net/ethernet/mellanox/mlx4/cq.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/net/ethernet/mellanox/mlx4/cq.c b/drivers/net/ethernet/mellanox/mlx4/cq.c
> > index 4d4f9cf9facb..7dadd7227480 100644
> > --- a/drivers/net/ethernet/mellanox/mlx4/cq.c
> > +++ b/drivers/net/ethernet/mellanox/mlx4/cq.c
> > @@ -315,7 +315,11 @@ static int mlx4_init_user_cqes(void *buf, int entries, int cqe_size)
> >  		}
> >  	} else {
> >  		err = copy_to_user((void __user *)buf, init_ents,
> > +#ifdef CONFIG_64BIT
> >  				   array_size(entries, cqe_size)) ?
> > +#else
> > +				   entries * cqe_size) ?
> > +#endif
> >  			-EFAULT : 0;
> 
> This can't possibly make sense, Kees?

Uuuuh, that's really weird. What compiler version and arch? I'll see if
I can reproduce this.

-- 
Kees Cook