Re: [PATCH bpf-next v14 6/8] bpf: Add syscall common attributes support for map_create

[Leon Hwang <leon.hwang@linux.dev>]

On 2026/5/14 08:46, sashiko-bot@kernel.org wrote:
[...]
>> +
>> +	err = __map_create(attr, uattr, log);
>> +
>> +	/* preserve original error even if log finalization is successful */
>> +	ret = bpf_log_attr_finalize(&attr_log, log);
>> +	if (ret) {
>> +		if (err >= 0)
>> +			close_fd(err);
> 
> Since __map_create() has already successfully created the map and installed
> the file descriptor via fd_install(), the fd is globally visible to the
> process at this point.
> 
> If bpf_log_attr_finalize() fails (for example, due to an invalid pointer
> for log_true_size), we attempt to roll back by calling close_fd(err) and
> returning an error.
> 
> Could this race with a concurrent thread?
> 
> If another thread closes this fd and opens a new file between fd_install()
> and this close_fd() call, wouldn't we erroneously close an unrelated file?
> 
> Also, if another thread dups the fd before we close it, wouldn't the BPF
> map remain alive and accessible to userspace even though the map_create
> syscall returned a failure?
> 

Replied in v13
https://lore.kernel.org/bpf/3c9b4ff0-7a62-4053-83c7-23151905c742@linux.dev/.

Thanks,
Leon

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