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Date: Tue, 25 May 2021 09:30:18 +0300
From: Alexey Izbyshev <izbyshev@...ras.ru>
To: Rich Felker <dalias@...c.org>
Cc: musl@...ts.openwall.com
Subject: Re: Potentially infinite loop in posix_spawn'ed child
On 2021-05-24 23:33, Rich Felker wrote:
> On Mon, May 24, 2021 at 01:09:21PM +0300, Alexey Izbyshev wrote:
>> Hi,
>>
>> I've noticed the following loop at
>> https://git.musl-libc.org/cgit/musl/tree/src/process/posix_spawn.c#n159:
>>
>> exec(args->path, args->argv, args->envp);
>> ret = -errno;
>>
>> fail:
>> /* Since sizeof errno < PIPE_BUF, the write is atomic. */
>> ret = -ret;
>> if (ret) while (__syscall(SYS_write, p, &ret, sizeof ret) < 0);
>> _exit(127);
>>
>> Is there any reason that write is done in a loop? If SIGPIPE is
>> blocked or ignored and the parent dies before this point, the child
>> will spin in it forever.
>
> I suppose the special case of EPIPE should be considered here as no
> need to inform the parent. Are there any other errors that should be
> treated specially?
>
I'm not aware of any other errors that would need treatment. Is this
loop intended to be a detection/debugging aid in case of an unexpected
error?
Alexey
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