netdev - Re: [PATCHv2] tools bpftool: Fix json dump crash on powerpc

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Message-ID: <83d18af0-8efa-c8d5-3d99-01aed29915df@netronome.com>
Date:   Fri, 5 Jul 2019 18:26:40 +0100
From:   Quentin Monnet <quentin.monnet@...ronome.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Jiri Olsa <jolsa@...hat.com>
Cc:     Jiri Olsa <jolsa@...nel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Michael Petlan <mpetlan@...hat.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Martin KaFai Lau <kafai@...com>
Subject: Re: [PATCHv2] tools bpftool: Fix json dump crash on powerpc

2019-07-05 10:24 UTC-0700 ~ Jakub Kicinski <jakub.kicinski@...ronome.com>
> On Fri, 5 Jul 2019 14:10:31 +0200, Jiri Olsa wrote:
>> Michael reported crash with by bpf program in json mode on powerpc:
>>
>>   # bpftool prog -p dump jited id 14
>>   [{
>>         "name": "0xd00000000a9aa760",
>>         "insns": [{
>>                 "pc": "0x0",
>>                 "operation": "nop",
>>                 "operands": [null
>>                 ]
>>             },{
>>                 "pc": "0x4",
>>                 "operation": "nop",
>>                 "operands": [null
>>                 ]
>>             },{
>>                 "pc": "0x8",
>>                 "operation": "mflr",
>>   Segmentation fault (core dumped)
>>
>> The code is assuming char pointers in format, which is not always
>> true at least for powerpc. Fixing this by dumping the whole string
>> into buffer based on its format.
>>
>> Please note that libopcodes code does not check return values from
>> fprintf callback, but as per Jakub suggestion returning -1 on allocation
>> failure so we do the best effort to propagate the error. 
>>
>> Reported-by: Michael Petlan <mpetlan@...hat.com>
>> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> 
> Thanks, let me repost all the tags (Quentin, please shout if you're
> not ok with this :)):

I confirm it's all good for me, thanks :)

> 
> Fixes: 107f041212c1 ("tools: bpftool: add JSON output for `bpftool prog dump jited *` command")
> Reviewed-by: Quentin Monnet <quentin.monnet@...ronome.com>
> Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
>