linux-kernel - Re: [PATCH] bpf: propagate _

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Date:   Mon, 7 Dec 2020 08:12:05 -0800
From:   Yonghong Song <yhs@...com>
To:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, <netdev@...r.kernel.org>,
        <bpf@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Martin KaFai Lau <kafai@...com>, Song Liu <songliubraving@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH] bpf: propagate __user annotations properly



On 12/7/20 4:37 AM, Lukas Bulwahn wrote:
> __htab_map_lookup_and_delete_batch() stores a user pointer in the local
> variable ubatch and uses that in copy_{from,to}_user(), but ubatch misses a
> __user annotation.
> 
> So, sparse warns in the various assignments and uses of ubatch:
> 
>    kernel/bpf/hashtab.c:1415:24: warning: incorrect type in initializer
>      (different address spaces)
>    kernel/bpf/hashtab.c:1415:24:    expected void *ubatch
>    kernel/bpf/hashtab.c:1415:24:    got void [noderef] __user *
> 
>    kernel/bpf/hashtab.c:1444:46: warning: incorrect type in argument 2
>      (different address spaces)
>    kernel/bpf/hashtab.c:1444:46:    expected void const [noderef] __user *from
>    kernel/bpf/hashtab.c:1444:46:    got void *ubatch
> 
>    kernel/bpf/hashtab.c:1608:16: warning: incorrect type in assignment
>      (different address spaces)
>    kernel/bpf/hashtab.c:1608:16:    expected void *ubatch
>    kernel/bpf/hashtab.c:1608:16:    got void [noderef] __user *
> 
>    kernel/bpf/hashtab.c:1609:26: warning: incorrect type in argument 1
>      (different address spaces)
>    kernel/bpf/hashtab.c:1609:26:    expected void [noderef] __user *to
>    kernel/bpf/hashtab.c:1609:26:    got void *ubatch
> 
> Add the __user annotation to repair this chain of propagating __user
> annotations in __htab_map_lookup_and_delete_batch().

Add fix tag?

Fixes: 057996380a42 ("bpf: Add batch ops to all htab bpf map")

> 
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>

Thanks for the fix. LGTM. I guess either bpf or bpf-next tree is fine
since this is not a correctness issue.

Acked-by: Yonghong Song <yhs@...com>