[gcc r12-3977] Plug possible snprintf overflow in lto-wrapper.

[gcc r12-3977] Plug possible snprintf overflow in lto-wrapper.

[Aldy Hernandez]

https://gcc.gnu.org/g:f5440ac7ad535edcf143a877c3da11a41cbf2c37

commit r12-3977-gf5440ac7ad535edcf143a877c3da11a41cbf2c37
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Tue Sep 28 15:54:20 2021 +0200

    Plug possible snprintf overflow in lto-wrapper.
    
    My upcoming improvements to the DOM threader triggered a warning in
    this code.  It looks like the format string is ".ltrans%u.ltrans", but
    we're only writing a max of ".ltrans" + whatever the MAX_INT is here.
    
    Tested on x86-64 Linux.
    
    gcc/ChangeLog:
    
            * lto-wrapper.c (run_gcc): Plug snprintf overflow.

Diff:
---
 gcc/lto-wrapper.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
index 903c258a03a..7b9e4883f38 100644
--- a/gcc/lto-wrapper.c
+++ b/gcc/lto-wrapper.c
@@ -1983,7 +1983,9 @@ cont:
 	  output_name = XOBFINISH (&env_obstack, char *);
 
 	  /* Adjust the dumpbase if the linker output file was seen.  */
-	  int dumpbase_len = (strlen (dumppfx) + sizeof (DUMPBASE_SUFFIX));
+	  int dumpbase_len = (strlen (dumppfx)
+			      + sizeof (DUMPBASE_SUFFIX)
+			      + sizeof (".ltrans"));
 	  char *dumpbase = (char *) xmalloc (dumpbase_len + 1);
 	  snprintf (dumpbase, dumpbase_len, "%sltrans%u.ltrans", dumppfx, i);
 	  argv_ptr[0] = dumpbase;
@@ -2009,9 +2011,11 @@ cont:
 	    }
 	  else
 	    {
-	      char argsuffix[sizeof (DUMPBASE_SUFFIX) + 1];
+	      char argsuffix[sizeof (DUMPBASE_SUFFIX)
+			     + sizeof (".ltrans_args") + 1];
 	      if (save_temps)
-		snprintf (argsuffix, sizeof (DUMPBASE_SUFFIX),
+		snprintf (argsuffix,
+			  sizeof (DUMPBASE_SUFFIX) + sizeof (".ltrans_args"),
 			  "ltrans%u.ltrans_args", i);
 	      fork_execute (new_argv[0], CONST_CAST (char **, new_argv),
 			    true, save_temps ? argsuffix : NULL);