commit e73fd06b7f12d6ddaae4f91f9c5088a621a82ce4
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon Aug 19 15:48:03 2024 +0200

    string: strerror, strsignal cannot use buffer after dlmopen (bug 32026)
    
    Secondary namespaces have a different malloc.  Allocating the
    buffer in one namespace and freeing it another results in
    heap corruption.  Fix this by using a static string (potentially
    translated) in secondary namespaces.  It would also be possible
    to use the malloc from the initial namespace to manage the
    buffer, but these functions would still not be safe to use in
    auditors etc. because a call to strerror could still free a
    buffer while it is used by the application.  Another approach
    could use proper initial-exec TLS, duplicated in secondary
    namespaces, but that would need a callback interface for freeing
    libc resources in namespaces on thread exit, which does not exist
    today.
    
    Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
    (cherry picked from commit 25a5eb4010df94b412c67db9e346029de316d06b)

diff --git a/string/strerror_l.c b/string/strerror_l.c
index 15cce261e6b406a7..70456e5bb45e5b52 100644
--- a/string/strerror_l.c
+++ b/string/strerror_l.c
@@ -20,7 +20,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <tls-internal.h>
-
+#include <libc-internal.h>
 
 static const char *
 translate (const char *str, locale_t loc)
@@ -31,6 +31,12 @@ translate (const char *str, locale_t loc)
   return res;
 }
 
+static char *
+unknown_error (locale_t loc)
+{
+  return (char *) translate ("Unknown error", loc);
+}
+
 
 /* Return a string describing the errno code in ERRNUM.  */
 char *
@@ -40,18 +46,25 @@ __strerror_l (int errnum, locale_t loc)
   char *err = (char *) __get_errlist (errnum);
   if (__glibc_unlikely (err == NULL))
     {
-      struct tls_internal_t *tls_internal = __glibc_tls_internal ();
-      free (tls_internal->strerror_l_buf);
-      if (__asprintf (&tls_internal->strerror_l_buf, "%s%d",
-		      translate ("Unknown error ", loc), errnum) > 0)
-	err = tls_internal->strerror_l_buf;
-      else
+      if (__libc_initial)
 	{
-	  /* The memory was freed above.  */
-	  tls_internal->strerror_l_buf = NULL;
-	  /* Provide a fallback translation.  */
-	  err = (char *) translate ("Unknown error", loc);
+	  struct tls_internal_t *tls_internal = __glibc_tls_internal ();
+	  free (tls_internal->strerror_l_buf);
+	  if (__asprintf (&tls_internal->strerror_l_buf, "%s%d",
+			  translate ("Unknown error ", loc), errnum) > 0)
+	    err = tls_internal->strerror_l_buf;
+	  else
+	    {
+	      /* The memory was freed above.  */
+	      tls_internal->strerror_l_buf = NULL;
+	      /* Provide a fallback translation.  */
+	      err = unknown_error (loc);
+	    }
 	}
+      else
+	/* Secondary namespaces use a different malloc, so cannot
+	   participate in the buffer management.  */
+	err = unknown_error (loc);
     }
   else
     err = (char *) translate (err, loc);
diff --git a/string/strsignal.c b/string/strsignal.c
index 31146015647c1d4a..d9b03654683a6805 100644
--- a/string/strsignal.c
+++ b/string/strsignal.c
@@ -21,6 +21,7 @@
 #include <string.h>
 #include <libintl.h>
 #include <tls-internal.h>
+#include <libc-internal.h>
 
 /* Return a string describing the meaning of the signal number SIGNUM.  */
 char *
@@ -30,21 +31,28 @@ strsignal (int signum)
   if (desc != NULL)
     return _(desc);
 
-  struct tls_internal_t *tls_internal = __glibc_tls_internal ();
-  free (tls_internal->strsignal_buf);
+  if (__libc_initial)
+    {
+      struct tls_internal_t *tls_internal = __glibc_tls_internal ();
+      free (tls_internal->strsignal_buf);
 
-  int r;
+      int r;
 #ifdef SIGRTMIN
-  if (signum >= SIGRTMIN && signum <= SIGRTMAX)
-    r = __asprintf (&tls_internal->strsignal_buf, _("Real-time signal %d"),
-		    signum - SIGRTMIN);
-  else
+      if (signum >= SIGRTMIN && signum <= SIGRTMAX)
+	r = __asprintf (&tls_internal->strsignal_buf, _("Real-time signal %d"),
+			signum - SIGRTMIN);
+      else
 #endif
-    r = __asprintf (&tls_internal->strsignal_buf, _("Unknown signal %d"),
-		    signum);
-
-  if (r == -1)
-    tls_internal->strsignal_buf = NULL;
-
-  return tls_internal->strsignal_buf;
+	r = __asprintf (&tls_internal->strsignal_buf, _("Unknown signal %d"),
+			signum);
+
+      if (r >= 0)
+	return tls_internal->strsignal_buf;
+      else
+	tls_internal->strsignal_buf = NULL;
+    }
+  /* Fall through on asprintf error, and for !__libc_initial:
+     secondary namespaces use a different malloc and cannot
+     participate in the buffer management.  */
+  return _("Unknown signal");
 }