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

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Date: Fri, 24 May 2024 06:36:19 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Shung-Hsi Yu <shung-hsi.yu@...e.com>
Cc: cve@...nel.org, 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 Fri, May 24, 2024 at 11:58:54AM +0800, Shung-Hsi Yu wrote:
> 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.

You are right, sorry about that, now rejected.  Thanks for the review!

greg k-h