[glibc/release/2.34/master] elf: Fix hwcaps string size overestimation

[Florian Weimer <fw@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2ff6775ad341b10a08e3b27d6e1df1da637747c7

commit 2ff6775ad341b10a08e3b27d6e1df1da637747c7
Author: Javier Pello <devel@otheo.eu>
Date:   Mon Sep 5 20:09:01 2022 +0200

    elf: Fix hwcaps string size overestimation
    
    Commit dad90d528259b669342757c37dedefa8577e2636 added glibc-hwcaps
    support for LD_LIBRARY_PATH and, for this, it adjusted the total
    string size required in _dl_important_hwcaps. However, in doing so
    it inadvertently altered the calculation of the size required for
    the power set strings, as the computation of the power set string
    size depended on the first value assigned to the total variable,
    which is later shifted, resulting in overallocation of string
    space. Fix this now by using a different variable to hold the
    string size required for glibc-hwcaps.
    
    Signed-off-by: Javier Pello <devel@otheo.eu>
    (cherry picked from commit a23820f6052a740246fdc7dcd9c43ce8eed0c45a)

Diff:
---
 elf/dl-hwcaps.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/elf/dl-hwcaps.c b/elf/dl-hwcaps.c
index e3c611e005..045911eb6d 100644
--- a/elf/dl-hwcaps.c
+++ b/elf/dl-hwcaps.c
@@ -193,7 +193,7 @@ _dl_important_hwcaps (const char *glibc_hwcaps_prepend,
   /* Each hwcaps subdirectory has a GLIBC_HWCAPS_PREFIX string prefix
      and a "/" suffix once stored in the result.  */
   hwcaps_counts.maximum_length += strlen (GLIBC_HWCAPS_PREFIX) + 1;
-  size_t total = (hwcaps_counts.count * (strlen (GLIBC_HWCAPS_PREFIX) + 1)
+  size_t hwcaps_sz = (hwcaps_counts.count * (strlen (GLIBC_HWCAPS_PREFIX) + 1)
 		  + hwcaps_counts.total_length);
 
   /* Count the number of bits set in the masked value.  */
@@ -229,11 +229,12 @@ _dl_important_hwcaps (const char *glibc_hwcaps_prepend,
   assert (m == cnt);
 
   /* Determine the total size of all strings together.  */
+  size_t total;
   if (cnt == 1)
-    total += temp[0].len + 1;
+    total = temp[0].len + 1;
   else
     {
-      total += temp[0].len + temp[cnt - 1].len + 2;
+      total = temp[0].len + temp[cnt - 1].len + 2;
       if (cnt > 2)
 	{
 	  total <<= 1;
@@ -255,6 +256,7 @@ _dl_important_hwcaps (const char *glibc_hwcaps_prepend,
   /* This is the overall result, including both glibc-hwcaps
      subdirectories and the legacy hwcaps subdirectories using the
      power set construction.  */
+  total += hwcaps_sz;
   struct r_strlenpair *overall_result
     = malloc (*sz * sizeof (*result) + total);
   if (overall_result == NULL)