[glibc] posix: Use malloc instead of alloca for the glob brace expansion

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=563f02a6aa0f37fd20ef8c78dc8b4a484a5355fb

commit 563f02a6aa0f37fd20ef8c78dc8b4a484a5355fb
Author: Adhemerval Zanella <[email protected]>
Date:   Fri Jul 31 18:06:02 2026 +0000

    posix: Use malloc instead of alloca for the glob brace expansion
    
    The last alloca in __glob is the buffer holding one expansion of a
    brace expression.  As with the directory and user names, the stack it
    takes is not bounded by the call itself.
    
    Use malloc unconditionally.  __glob no longer uses alloca; glob_in_dir
    still does, so the accounting stays for now.
    
    Checked on x86_64-linux-gnu, aarch64-linux-gnu, and i686-linux-gnu.
    
    Reviewed-by: Collin Funk <[email protected]>

Diff:
---
 posix/glob.c | 22 +++++++---------------
 1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/posix/glob.c b/posix/glob.c
index a3c1f888d5..f1380cf596 100644
--- a/posix/glob.c
+++ b/posix/glob.c
@@ -485,15 +485,10 @@ __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
           size_t rest_len;
           char *onealt;
           size_t pattern_len = strlen (pattern) - 1;
-          int alloca_onealt = glob_use_alloca (alloca_used, pattern_len);
-          if (alloca_onealt)
-            onealt = alloca_account (pattern_len, alloca_used);
-          else
-            {
-              onealt = malloc (pattern_len);
-              if (onealt == NULL)
-                return GLOB_NOSPACE;
-            }
+
+          onealt = malloc (pattern_len);
+          if (onealt == NULL)
+            return GLOB_NOSPACE;
 
           /* We know the prefix for all sub-patterns.  */
           alt_start = mempcpy (onealt, pattern, begin - pattern);
@@ -505,8 +500,7 @@ __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
             {
               /* It is an invalid expression.  */
             illegal_brace:
-              if (__glibc_unlikely (!alloca_onealt))
-                free (onealt);
+              free (onealt);
               flags &= ~GLOB_BRACE;
               goto no_brace;
             }
@@ -547,8 +541,7 @@ __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
               /* If we got an error, return it.  */
               if (result && result != GLOB_NOMATCH)
                 {
-                  if (__glibc_unlikely (!alloca_onealt))
-                    free (onealt);
+                  free (onealt);
                   if (!(flags & GLOB_APPEND))
                     {
                       globfree (pglob);
@@ -566,8 +559,7 @@ __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
               assert (next != NULL);
             }
 
-          if (__glibc_unlikely (!alloca_onealt))
-            free (onealt);
+          free (onealt);
 
           if (pglob->gl_pathc != firstc)
             /* We found some entries.  */