[glibc/release/2.36/master] elf: Replace `strcpy` call with `memcpy` [BZ #29454]

[Noah Goldstein <nwg@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=302bc33bc53c787da6e74162a7092e9c0fb964a8

commit 302bc33bc53c787da6e74162a7092e9c0fb964a8
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Mon Aug 8 11:26:22 2022 +0800

    elf: Replace `strcpy` call with `memcpy` [BZ #29454]
    
    GCC normally does this optimization for us in
    strlen_pass::handle_builtin_strcpy but only for optimized
    build. To avoid needing to include strcpy.S in the rtld build to
    support the debug build, just do the optimization by hand.
    
    (cherry picked from commit 483cfe1a6a33d6335b1901581b41040d2d412511)

Diff:
---
 elf/dl-cache.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/elf/dl-cache.c b/elf/dl-cache.c
index 8bbf110d02..b97c17b3a9 100644
--- a/elf/dl-cache.c
+++ b/elf/dl-cache.c
@@ -509,8 +509,9 @@ _dl_load_cache_lookup (const char *name)
      we are accessing. Therefore we must make the copy of the
      mapping data without using malloc.  */
   char *temp;
-  temp = alloca (strlen (best) + 1);
-  strcpy (temp, best);
+  size_t best_len = strlen (best) + 1;
+  temp = alloca (best_len);
+  memcpy (temp, best, best_len);
   return __strdup (temp);
 }