upstream

1 files changed, 5 insertions, 3 deletions

diff --git a/src/sysdep.c b/src/sysdep.c
index 4bd1f54b9e6..57fff94f552 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -2640,7 +2640,7 @@ system_process_attributes (Lisp_Object pid)
   ssize_t nread;
   const char *cmd = NULL;
   char *cmdline = NULL;
-  size_t cmdsize = 0, cmdline_size;
+  ptrdiff_t cmdsize = 0, cmdline_size;
   unsigned char c;
   int proc_id, ppid, uid, gid, pgrp, sess, tty, tpgid, thcount;
   unsigned long long u_time, s_time, cutime, cstime, start;
@@ -2822,8 +2822,10 @@ system_process_attributes (Lisp_Object pid)
   if (fd >= 0)
     {
       char ch;
-      for (cmdline_size = 0; emacs_read (fd, &ch, 1) == 1; cmdline_size++)
+      for (cmdline_size = 0; cmdline_size < STRING_BYTES_BOUND; cmdline_size++)
         {
+          if (emacs_read (fd, &ch, 1) != 1)
+            break;
           c = ch;
           if (isspace (c) || c == '\\')
             cmdline_size++;     /* for later quoting, see below */
@@ -2844,7 +2846,7 @@ system_process_attributes (Lisp_Object pid)
               nread = 0;
             }
           /* We don't want trailing null characters.  */
-          for (p = cmdline + nread - 1; p > cmdline && !*p; p--)
+          for (p = cmdline + nread; p > cmdline + 1 && !p[-1]; p--)
             nread--;
           for (p = cmdline; p < cmdline + nread; p++)
             {