linux-kernel - Re: CVE-2023-52793: samples/bpf: syscall_tp

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Date: Fri, 24 May 2024 11:58:54 +0800
From: Shung-Hsi Yu <shung-hsi.yu@...e.com>
To: cve@...nel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...e.com>
Subject: Re: CVE-2023-52793: samples/bpf: syscall_tp_user: Fix array
 out-of-bound access

On Tue, 21 May 2024 17:31:29 +0200, Greg Kroah-Hartman wrote:
> Description
> ===========
> 
> In the Linux kernel, the following vulnerability has been resolved:
> 
> samples/bpf: syscall_tp_user: Fix array out-of-bound access
> 
> Commit 06744f24696e ("samples/bpf: Add openat2() enter/exit tracepoint
> to syscall_tp sample") added two more eBPF programs to support the
> openat2() syscall. However, it did not increase the size of the array
> that holds the corresponding bpf_links. This leads to an out-of-bound
> access on that array in the bpf_object__for_each_program loop and could
> corrupt other variables on the stack. On our testing QEMU, it corrupts
> the map1_fds array and causes the sample to fail:
> 
>   # ./syscall_tp
>   prog #0: map ids 4 5
>   verify map:4 val: 5
>   map_lookup failed: Bad file descriptor
> 
> Dynamically allocate the array based on the number of programs reported
> by libbpf to prevent similar inconsistencies in the future
> 
> The Linux kernel CVE team has assigned CVE-2023-52793 to this issue.

I would like to dispute this CVE.

Files in samples/bpf are meant to serve as an example and not code that
are directly used at run-time, hence I believe this bug does not have
security implication.

--
Shung-Hsi Yu

> ...