[PATCH] examples/qos_sched: fix build with LTO

[PATCH] examples/qos_sched: fix build with LTO

[Stephen Hemminger]

rte_cfgfile_section_num_entries() returns -1 on error, which is used
unchecked as a VLA size. With LTO gcc inlines the library call, sees
the -1 path and fails with -Wvla-larger-than.

Return error if the entry count is negative.

Fixes: db935d0171dd ("examples/qos_sched: use librte_cfgfile")
Cc: stable@dpdk.org

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 examples/qos_sched/cfg_file.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/examples/qos_sched/cfg_file.c b/examples/qos_sched/cfg_file.c
index 3ca06c2ff9..e73d9f7cdd 100644
--- a/examples/qos_sched/cfg_file.c
+++ b/examples/qos_sched/cfg_file.c
@@ -438,6 +438,9 @@ cfg_load_subport(struct rte_cfgfile *cfg)
 			}
 
 			int n_entries = rte_cfgfile_section_num_entries(cfg, sec_name);
+			if (n_entries < 0)
+				return -1;
+
 			struct rte_cfgfile_entry entries[n_entries];
 
 			rte_cfgfile_section_entries(cfg, sec_name, entries, n_entries);
-- 
2.53.0

Re: [PATCH] examples/qos_sched: fix build with LTO

[Bruce Richardson]

On Mon, Nov 09, 2026 at 06:04:03PM -0800, Stephen Hemminger wrote:
> rte_cfgfile_section_num_entries() returns -1 on error, which is used
> unchecked as a VLA size. With LTO gcc inlines the library call, sees
> the -1 path and fails with -Wvla-larger-than.
> 
> Return error if the entry count is negative.
> 
> Fixes: db935d0171dd ("examples/qos_sched: use librte_cfgfile")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  examples/qos_sched/cfg_file.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/examples/qos_sched/cfg_file.c b/examples/qos_sched/cfg_file.c
> index 3ca06c2ff9..e73d9f7cdd 100644
> --- a/examples/qos_sched/cfg_file.c
> +++ b/examples/qos_sched/cfg_file.c
> @@ -438,6 +438,9 @@ cfg_load_subport(struct rte_cfgfile *cfg)
>  			}
>  
>  			int n_entries = rte_cfgfile_section_num_entries(cfg, sec_name);
> +			if (n_entries < 0)
> +				return -1;
> +
>  			struct rte_cfgfile_entry entries[n_entries];

In practice I don't think that error case can occur, since an earlier check
verifies that the section exists. However, the check is harmless and not on
a fast-path.

Acked-by: Bruce Richardson <bruce.richardson@intel.com>

Re: [PATCH] examples/qos_sched: fix build with LTO

[Thomas Monjalon]

10/11/2026 10:05, Bruce Richardson:
> On Mon, Nov 09, 2026 at 06:04:03PM -0800, Stephen Hemminger wrote:
> > rte_cfgfile_section_num_entries() returns -1 on error, which is used
> > unchecked as a VLA size. With LTO gcc inlines the library call, sees
> > the -1 path and fails with -Wvla-larger-than.
> > 
> > Return error if the entry count is negative.
> > 
> > Fixes: db935d0171dd ("examples/qos_sched: use librte_cfgfile")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> 
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>

Applied, thanks.