On Thu, 4 Jul 2019 10:58:56 +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, so there's no point to return error in case of
> allocation failure.
Well, it doesn't check it today, it may perhaps do it in the future?
Let's flip the question - since it doesn't check it today, why not
propagate the error? :) We should stay close to how fprintf would
behave, IMHO.
Fixes: 107f041212c1 ("tools: bpftool: add JSON output for `bpftool prog dump jited *` command")
> Reported-by: Michael Petlan <mpetlan@xxxxxxxxxx>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
