[binutils-gdb] gdb: fix off-by-one error in quirk_rust_enum

[binutils-gdb] gdb: fix off-by-one error in quirk_rust_enum

[Simon Marchi]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f408d82c7a140268c3b7be35970c96d8385b5902

commit f408d82c7a140268c3b7be35970c96d8385b5902
Author: Simon Marchi <simon.marchi@efficios.com>
Date:   Tue May 19 14:20:23 2020 -0400

    gdb: fix off-by-one error in quirk_rust_enum
    
    Found by inspection, so I don't have a test for it (I don't think it
    would be easy to have this bug cause a failure reliably).
    
    We allocate space for N fields into `new_fields`, then memcpy N fields
    at `new_fields + 1`.  This overflows the allocated buffer by one field.
    
    Fix it by allocating `N + 1` fields.
    
    gdb/ChangeLog:
    
            * dwarf2/read.c (quirk_rust_enum): Allocate enough fields.

Diff:
---
 gdb/ChangeLog     | 4 ++++
 gdb/dwarf2/read.c | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index f62557da6c0..ac0beef5ad5 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2020-05-19  Simon Marchi  <simon.marchi@efficios.com>
+
+	* dwarf2/read.c (quirk_rust_enum): Allocate enough fields.
+
 2020-05-19  Pedro Alves  <palves@redhat.com>
 
 	* NEWS (set exec-file-mismatch): Adjust entry.
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 0c6182bbf3b..2ab7c5c3313 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -9420,7 +9420,7 @@ quirk_rust_enum (struct type *type, struct objfile *objfile)
       /* Make space for the discriminant field.  */
       struct field *disr_field = &TYPE_FIELD (disr_type, 0);
       field *new_fields
-	= (struct field *) TYPE_ZALLOC (type, (TYPE_NFIELDS (type)
+	= (struct field *) TYPE_ZALLOC (type, ((TYPE_NFIELDS (type) + 1)
 					       * sizeof (struct field)));
       memcpy (new_fields + 1, TYPE_FIELDS (type),
 	      TYPE_NFIELDS (type) * sizeof (struct field));