Re: [PATCH bpf-next v3 2/2] bpf: Check return from set_memory_rox()

From: Martin KaFai Lau <martin.lau@linux.dev>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>, Zi Shen Lim <zlim.lnx@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	David Ahern <dsahern@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Kui-Feng Lee <thinker.li@gmail.com>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH bpf-next v3 2/2] bpf: Check return from set_memory_rox()
Date: Fri, 15 Mar 2024 13:55:28 -0700	[thread overview]
Message-ID: <55151dc9-8edf-4c75-b1d0-1cc0437816c3@linux.dev> (raw)
In-Reply-To: <4d7cc25e937403ac61ae61be06f998f27e631a65.1710522112.git.christophe.leroy@csgroup.eu>

On 3/15/24 10:06 AM, Christophe Leroy wrote:
> diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
> index 43356faaa057..ca1d9b87c475 100644
> --- a/kernel/bpf/bpf_struct_ops.c
> +++ b/kernel/bpf/bpf_struct_ops.c
> @@ -742,8 +742,11 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
>   		if (err)
>   			goto reset_unlock;
>   	}
> -	for (i = 0; i < st_map->image_pages_cnt; i++)
> -		arch_protect_bpf_trampoline(st_map->image_pages[i], PAGE_SIZE);
> +	for (i = 0; i < st_map->image_pages_cnt && !err; i++)
> +		err = arch_protect_bpf_trampoline(st_map->image_pages[i], PAGE_SIZE);
> +
> +	if (err)
> +		goto reset_unlock;

This part does not look right. The "if (err)" check should be inside the for loop.

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