[DTrace-devel] [PATCH 1/4] bpf: fix file descriptor leak

[Eugene Loh]

Reviewed-by: Eugene Loh <eugene.loh at oracle.com>

But I'm curious about the "if (attach)" check.  It looks a little funny 
that we first set fd= and then we check "if (attach)" to see if we are 
going to use the fd value we just set.  I suppose it does not matter 
since we expect attach to be there, but normally one would first check 
if a value is needed before going to the trouble of determining the 
value.  In a way, this small, pre-existing issue is outside the scope of 
this patch, except that the patch makes more obvious the one, isolated 
place where this temporary value is used.

Up to you whether to clean that up.

On 11/10/25 10:27, Kris Van Hees via DTrace-devel wrote:
> When a BPF program has been attached to a perf event, it is safe to
> close its file descriptor.
>
> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> ---
>   libdtrace/dt_bpf.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libdtrace/dt_bpf.c b/libdtrace/dt_bpf.c
> index 0223764a..28eb890e 100644
> --- a/libdtrace/dt_bpf.c
> +++ b/libdtrace/dt_bpf.c
> @@ -1385,8 +1385,8 @@ dt_bpf_load_progs(dtrace_hdl_t *dtp, uint_t cflags)
>   		if (prp->prov->impl->attach)
>   			rc = prp->prov->impl->attach(dtp, prp, fd);
>   
> +		close(fd);
>   		if (rc < 0 && !(prp->flags & DT_PROBE_FLAG_OPTIONAL)) {
> -			close(fd);
>   			dt_attach_error(dtp, rc,
>   					prp->desc->prv, prp->desc->mod,
>   					prp->desc->fun, prp->desc->prb);