[glibc] elf: Emit warning if tunable is ill-formatted

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=eb9291aaa6ff6af158a1436b881ef8b834559621

commit eb9291aaa6ff6af158a1436b881ef8b834559621
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Mon Nov 6 17:25:41 2023 -0300

    elf: Emit warning if tunable is ill-formatted
    
    So caller knows that the tunable will be ignored.
    
    Checked on x86_64-linux-gnu.
    Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

Diff:
---
 elf/dl-tunables.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index 4d6a143f06..83265bc00b 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -235,6 +235,12 @@ parse_tunables (char *valstring)
 {
   struct tunable_toset_t tunables[tunables_list_size];
   int ntunables = parse_tunables_string (valstring, tunables);
+  if (ntunables == -1)
+    {
+      _dl_error_printf (
+        "WARNING: ld.so: invalid GLIBC_TUNABLES `%s': ignored.\n", valstring);
+      return;
+    }
 
   for (int i = 0; i < ntunables; i++)
     tunable_initialize (tunables[i].t, tunables[i].value);