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Subject: Re: [PATCH] bpf: Replace BUG_ON when fp_old is NULL
To:     Yonghong Song <yhs@fb.com>, Aditya Pakki <pakki001@umn.edu>
Cc:     "kjlu@umn.edu" <kjlu@umn.edu>, Alexei Starovoitov <ast@kernel.org>,
        Martin Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
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References: <20191215154432.22399-1-pakki001@umn.edu>
 <98c13b9c-a73a-6203-4ea1-6b1180d87d97@fb.com>
From:   Daniel Borkmann <daniel@iogearbox.net>
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Date:   Mon, 16 Dec 2019 12:17:50 +0100
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On 12/15/19 11:08 PM, Yonghong Song wrote:
> On 12/15/19 7:44 AM, Aditya Pakki wrote:
>> If fp_old is NULL in bpf_prog_realloc, the program does an assertion
>> and crashes. However, we can continue execution by returning NULL to
>> the upper callers. The patch fixes this issue.
> 
> Could you share how to reproduce the assertion and crash? I would
> like to understand the problem first before making changes in the code.
> Thanks!

Fully agree, Aditya, please elaborate if you have seen a crash!