[gcc r14-9348] Fortran: Fix issue with using snprintf function.

Jerry DeLisle jvdelisle@gcc.gnu.org
Thu Mar 7 03:58:07 GMT 2024


https://gcc.gnu.org/g:03932d3203bce244edd812b81921c2f16ea18d86

commit r14-9348-g03932d3203bce244edd812b81921c2f16ea18d86
Author: Jerry DeLisle <jvdelisle@gcc.gnu.org>
Date:   Wed Mar 6 19:46:04 2024 -0800

    Fortran: Fix issue with using snprintf function.
    
    The previous patch used snprintf to set the message
    string. The message string is not a formatted string
    and the snprintf will interpret '%' related characters
    as format specifiers when there are no associated
    output variables. A segfault ensues.
    
    This change replaces snprintf with a fortran string copy
    function and null terminates the message string.
    
            PR libfortran/105456
    
    libgfortran/ChangeLog:
    
            * io/list_read.c (list_formatted_read_scalar): Use fstrcpy
            from libgfortran/runtime/string.c to replace snprintf.
            (nml_read_obj): Likewise.
            * io/transfer.c (unformatted_read): Likewise.
            (unformatted_write): Likewise.
            (formatted_transfer_scalar_read): Likewise.
            (formatted_transfer_scalar_write): Likewise.
            * io/write.c (list_formatted_write_scalar): Likewise.
            (nml_write_obj): Likewise.
    
    gcc/testsuite/ChangeLog:
    
            * gfortran.dg/pr105456.f90: Revise using '%' characters
            in users error message.

Diff:
---
 gcc/testsuite/gfortran.dg/pr105456.f90 |  4 ++--
 libgfortran/io/list_read.c             | 10 ++++++----
 libgfortran/io/transfer.c              | 20 ++++++++++++--------
 libgfortran/io/write.c                 | 10 ++++++----
 4 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/gcc/testsuite/gfortran.dg/pr105456.f90 b/gcc/testsuite/gfortran.dg/pr105456.f90
index 188323847a7..60cd3b6f3e8 100644
--- a/gcc/testsuite/gfortran.dg/pr105456.f90
+++ b/gcc/testsuite/gfortran.dg/pr105456.f90
@@ -19,7 +19,7 @@ contains
     character :: ch
     read (unit,fmt='(A1)', advance="no", iostat=piostat, iomsg=piomsg) ch
     piostat = 42
-    piomsg="The users message"
+    piomsg="The users message containing % and %% and %s and other stuff"
     dtv%ch = ch
   end subroutine read_formatted
 end module sk1
@@ -35,4 +35,4 @@ program skip1
   write (*,'(10(A))') "Read: '",x%ch,"'"
 end program skip1
 ! { dg-output ".*(unit = 10, file = .*)" }
-! { dg-output "Fortran runtime error: The users message" }
+! { dg-output "Fortran runtime error: The users message containing % and %% and %s and other stuff" }
diff --git a/libgfortran/io/list_read.c b/libgfortran/io/list_read.c
index 707afaeb8dc..e38e9a84976 100644
--- a/libgfortran/io/list_read.c
+++ b/libgfortran/io/list_read.c
@@ -2268,9 +2268,10 @@ list_formatted_read_scalar (st_parameter_dt *dtp, bt type, void *p,
 	      !(dtp->common.flags & IOPARM_HAS_IOSTAT))
 	    {
 	      char message[IOMSG_LEN + 1];
-	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg) + 1;
+	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg);
 	      free_line (dtp);
-	      snprintf (message, child_iomsg_len, child_iomsg);
+	      fstrcpy (message, child_iomsg_len, child_iomsg, child_iomsg_len);
+	      message[child_iomsg_len] = '\0';
 	      generate_error (&dtp->common, dtp->u.p.child_saved_iostat,
 			      message);
 	    }
@@ -3082,8 +3083,9 @@ nml_read_obj (st_parameter_dt *dtp, namelist_info *nl, index_type offset,
 		    !(dtp->common.flags & IOPARM_HAS_IOSTAT))
 		  {
 		    char message[IOMSG_LEN + 1];
-		    child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg) + 1;
-		    snprintf (message, child_iomsg_len, child_iomsg);
+		    child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg);
+		    fstrcpy (message, child_iomsg_len, child_iomsg, child_iomsg_len);
+		    message[child_iomsg_len] = '\0';
 		    generate_error (&dtp->common, dtp->u.p.child_saved_iostat,
 				    message);
 		    goto nml_err_ret;
diff --git a/libgfortran/io/transfer.c b/libgfortran/io/transfer.c
index 9523a14c4bf..a86099d46f5 100644
--- a/libgfortran/io/transfer.c
+++ b/libgfortran/io/transfer.c
@@ -1128,8 +1128,9 @@ unformatted_read (st_parameter_dt *dtp, bt type,
 	      !(dtp->common.flags & IOPARM_HAS_IOSTAT))
 	    {
 	      char message[IOMSG_LEN + 1];
-	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg) + 1;
-	      snprintf (message, child_iomsg_len, child_iomsg);
+	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg);
+	      fstrcpy (message, child_iomsg_len, child_iomsg, child_iomsg_len);
+	      message[child_iomsg_len] = '\0';
 	      generate_error (&dtp->common, dtp->u.p.child_saved_iostat,
 			      message);
 	    }
@@ -1271,8 +1272,9 @@ unformatted_write (st_parameter_dt *dtp, bt type,
 	      !(dtp->common.flags & IOPARM_HAS_IOSTAT))
 	    {
 	      char message[IOMSG_LEN + 1];
-	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg) + 1;
-	      snprintf (message, child_iomsg_len, child_iomsg);
+	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg);
+	      fstrcpy (message, child_iomsg_len, child_iomsg, child_iomsg_len);
+	      message[child_iomsg_len] = '\0';
 	      generate_error (&dtp->common, dtp->u.p.child_saved_iostat,
 			      message);
 	    }
@@ -1763,8 +1765,9 @@ formatted_transfer_scalar_read (st_parameter_dt *dtp, bt type, void *p, int kind
 	      !(dtp->common.flags & IOPARM_HAS_IOSTAT))
 	    {
 	      char message[IOMSG_LEN + 1];
-	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg) + 1;
-	      snprintf (message, child_iomsg_len, child_iomsg);
+	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg);
+	      fstrcpy (message, child_iomsg_len, child_iomsg, child_iomsg_len);
+	      message[child_iomsg_len] = '\0';
 	      generate_error (&dtp->common, dtp->u.p.child_saved_iostat,
 			      message);
 	    }
@@ -2259,8 +2262,9 @@ formatted_transfer_scalar_write (st_parameter_dt *dtp, bt type, void *p, int kin
 	      !(dtp->common.flags & IOPARM_HAS_IOSTAT))
 	    {
 	      char message[IOMSG_LEN + 1];
-	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg) + 1;
-	      snprintf (message, child_iomsg_len, child_iomsg);
+	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg);
+	      fstrcpy (message, child_iomsg_len, child_iomsg, child_iomsg_len);
+	      message[child_iomsg_len] = '\0';
 	      generate_error (&dtp->common, dtp->u.p.child_saved_iostat,
 			      message);
 	    }
diff --git a/libgfortran/io/write.c b/libgfortran/io/write.c
index cdcaf8decb6..91d1da2007a 100644
--- a/libgfortran/io/write.c
+++ b/libgfortran/io/write.c
@@ -1999,8 +1999,9 @@ list_formatted_write_scalar (st_parameter_dt *dtp, bt type, void *p, int kind,
 	      !(dtp->common.flags & IOPARM_HAS_IOSTAT))
 	    {
 	      char message[IOMSG_LEN + 1];
-	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg) + 1;
-	      snprintf (message, child_iomsg_len, child_iomsg);
+	      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg);
+	      fstrcpy (message, child_iomsg_len, child_iomsg, child_iomsg_len);
+	      message[child_iomsg_len] = '\0';
 	      generate_error (&dtp->common, dtp->u.p.child_saved_iostat,
 			      message);
 	    }
@@ -2352,8 +2353,9 @@ nml_write_obj (st_parameter_dt *dtp, namelist_info *obj, index_type offset,
 		      char message[IOMSG_LEN + 1];
 
 		      /* Trim trailing spaces from the message.  */
-		      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg) + 1;
-		      snprintf (message, child_iomsg_len, child_iomsg);
+		      child_iomsg_len = string_len_trim (IOMSG_LEN, child_iomsg);
+		      fstrcpy (message, child_iomsg_len, child_iomsg, child_iomsg_len);
+		      message[child_iomsg_len] = '\0';
 		      generate_error (&dtp->common, dtp->u.p.child_saved_iostat,
 				      message);
 		    }


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