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From: Yonghong Song <yhs@fb.com>
To: KP Singh <kpsingh@kernel.org>, <bpf@vger.kernel.org>
Cc: Gilad Reti <gilad.reti@gmail.com>,
	Martin KaFai Lau <kafai@fb.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Subject: Re: [PATCH bpf v2 2/3] bpf: local storage helpers should check nullness of owner ptr passed
Date: Mon, 11 Jan 2021 23:25:47 -0800	[thread overview]
Message-ID: <f4e35851-7273-3b9f-3b11-e2e7ae05f67c@fb.com> (raw)
In-Reply-To: <20210111212340.86393-3-kpsingh@kernel.org>



On 1/11/21 1:23 PM, KP Singh wrote:
> The verifier allows ARG_PTR_TO_BTF_ID helper arguments to be NULL, so
> helper implementations need to check this before dereferencing them.
> This was already fixed for the socket storage helpers but not for task
> and inode.
> 
> The issue can be reproduced by attaching an LSM program to
> inode_rename hook (called when moving files) which tries to get the
> inode of the new file without checking for its nullness and then trying
> to move an existing file to a new path:
> 
>    mv existing_file new_file_does_not_exist
> 
> The report including the sample program and the steps for reproducing
> the bug:
> 
>    https://lore.kernel.org/bpf/CANaYP3HWkH91SN=wTNO9FL_2ztHfqcXKX38SSE-JJ2voh+vssw@mail.gmail.com
> 
> Fixes: 4cf1bc1f1045 ("bpf: Implement task local storage")
> Fixes: 8ea636848aca ("bpf: Implement bpf_local_storage for inodes")
> Reported-by: Gilad Reti <gilad.reti@gmail.com>
> Acked-by: Martin KaFai Lau <kafai@fb.com>
> Signed-off-by: KP Singh <kpsingh@kernel.org>

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

  reply	other threads:[~2021-01-12  7:26 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-11 21:23 [PATCH bpf v2 0/3] Fix local storage helper OOPs KP Singh
2021-01-11 21:23 ` [PATCH bpf v2 1/3] bpf: update local storage test to check handling of null ptrs KP Singh
2021-01-12  7:24   ` Yonghong Song
2021-01-12  7:35     ` KP Singh
2021-01-11 21:23 ` [PATCH bpf v2 2/3] bpf: local storage helpers should check nullness of owner ptr passed KP Singh
2021-01-12  7:25   ` Yonghong Song [this message]
2021-01-11 21:23 ` [PATCH bpf v2 3/3] bpf: Fix typo in bpf_inode_storage.c KP Singh
2021-01-12  7:26   ` Yonghong Song

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