libpam: fix w/musl after update to 1.3.1

pkgs/os-specific/linux/pam/default.nix

@@ -18,10 +18,9 @@ stdenv.mkDerivation rec {
       url = "https://git.alpinelinux.org/cgit/aports/plain/main/linux-pam/libpam-fix-build-with-eglibc-2.16.patch?id=05a62bda8ec255d7049a2bd4cf0fdc4b32bdb2cc";
       sha256 = "1ib6shhvgzinjsc603k2x1lxh9dic6qq449fnk110gc359m23j81";
     })
-    (fetchpatch {
+    # From adelie's package repo, using local copy since it seems to be currently offline.
-      url = "https://git.alpinelinux.org/cgit/aports/plain/main/linux-pam/musl-fix-pam_exec.patch?id=05a62bda8ec255d7049a2bd4cf0fdc4b32bdb2cc";
+    # (we previously used similar patch from void, but stopped working with update to 1.3.1)
-      sha256 = "04dx6s9d8cxl40r7m7dc4si47ds4niaqm7902y1d6wcjvs11vrf0";
+    ./musl-fix-pam_exec.patch
-    })
   ];
 
   outputs = [ "out" "doc" "man" /* "modules" */ ];

pkgs/os-specific/linux/pam/musl-fix-pam_exec.patch

@@ -0,0 +1,33 @@
+--- ./modules/pam_exec/pam_exec.c.orig
++++ ./modules/pam_exec/pam_exec.c
+@@ -103,11 +103,14 @@
+   int optargc;
+   const char *logfile = NULL;
+   const char *authtok = NULL;
++  char authtok_buf[PAM_MAX_RESP_SIZE+1];
++
+   pid_t pid;
+   int fds[2];
+   int stdout_fds[2];
+   FILE *stdout_file = NULL;
+ 
++  memset(authtok_buf, 0, sizeof(authtok_buf));
+   if (argc < 1) {
+     pam_syslog (pamh, LOG_ERR,
+ 		"This module needs at least one argument");
+@@ -180,12 +183,12 @@
+ 	      if (resp)
+ 		{
+ 		  pam_set_item (pamh, PAM_AUTHTOK, resp);
+-		  authtok = strndupa (resp, PAM_MAX_RESP_SIZE);
++		  authtok = strncpy(authtok_buf, resp, sizeof(authtok_buf));
+ 		  _pam_drop (resp);
+ 		}
+ 	    }
+ 	  else
+-	    authtok = strndupa (void_pass, PAM_MAX_RESP_SIZE);
++	    authtok = strncpy(authtok_buf, void_pass, sizeof(authtok_buf));
+ 
+ 	  if (pipe(fds) != 0)
+ 	    {
+