From: Tom Tromey <tromey@adacore.com>
Date: Tue, 31 Mar 2020 13:29:53 +0000 (-0600)
Subject: Don't pass NULL to memcpy in gdb
X-Git-Url: http://git.efficios.com/?a=commitdiff_plain;h=af62665e1339d970ab8ea3e3260dbdbde0009c2d;hp=16b0db75af6b4b4d434aa84c74d58b7290e04143;p=deliverable%2Fbinutils-gdb.git

Don't pass NULL to memcpy in gdb

I compiled gdb with -fsanitize=undefined and ran the test suite.

A couple of reports came from passing NULL to memcpy, e.g.:

[...]btrace-common.cc:176:13: runtime error: null pointer passed as argument 2, which is declared to never be null

While it would be better to fix this in the standard, in the meantime
it seems easy to avoid this error.

gdb/ChangeLog
2020-03-31  Tom Tromey  <tromey@adacore.com>

	* dwarf2/abbrev.c (abbrev_table::read): Conditionally call
	memcpy.

gdbsupport/ChangeLog
2020-03-31  Tom Tromey  <tromey@adacore.com>

	* btrace-common.cc (btrace_data_append): Conditionally call
	memcpy.
---

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 67aa872142..d3873da04b 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-31  Tom Tromey  <tromey@adacore.com>
+
+	* dwarf2/abbrev.c (abbrev_table::read): Conditionally call
+	memcpy.
+
 2020-03-30  Nelson Chu  <nelson.chu@sifive.com>
 
 	* features/riscv/32bit-csr.xml: Regenerated.
diff --git a/gdb/dwarf2/abbrev.c b/gdb/dwarf2/abbrev.c
index 59ff138b33..b85018060f 100644
--- a/gdb/dwarf2/abbrev.c
+++ b/gdb/dwarf2/abbrev.c
@@ -168,8 +168,9 @@ abbrev_table::read (struct objfile *objfile,
       cur_abbrev->attrs =
 	XOBNEWVEC (&abbrev_table->m_abbrev_obstack, struct attr_abbrev,
 		   cur_abbrev->num_attrs);
-      memcpy (cur_abbrev->attrs, cur_attrs.data (),
-	      cur_abbrev->num_attrs * sizeof (struct attr_abbrev));
+      if (!cur_attrs.empty ())
+	memcpy (cur_abbrev->attrs, cur_attrs.data (),
+		cur_abbrev->num_attrs * sizeof (struct attr_abbrev));
 
       abbrev_table->add_abbrev (abbrev_number, cur_abbrev);
 
diff --git a/gdbsupport/ChangeLog b/gdbsupport/ChangeLog
index 1d27971f5c..86233e8d0e 100644
--- a/gdbsupport/ChangeLog
+++ b/gdbsupport/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-31  Tom Tromey  <tromey@adacore.com>
+
+	* btrace-common.cc (btrace_data_append): Conditionally call
+	memcpy.
+
 2020-03-27  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* create-version.sh: Resolve issues highlighted by shellcheck.
diff --git a/gdbsupport/btrace-common.cc b/gdbsupport/btrace-common.cc
index 7d4f6424c8..e8b24db7d5 100644
--- a/gdbsupport/btrace-common.cc
+++ b/gdbsupport/btrace-common.cc
@@ -173,7 +173,8 @@ btrace_data_append (struct btrace_data *dst,
 	    size = src->variant.pt.size + dst->variant.pt.size;
 	    data = (gdb_byte *) xmalloc (size);
 
-	    memcpy (data, dst->variant.pt.data, dst->variant.pt.size);
+	    if (dst->variant.pt.size > 0)
+	      memcpy (data, dst->variant.pt.data, dst->variant.pt.size);
 	    memcpy (data + dst->variant.pt.size, src->variant.pt.data,
 		    src->variant.pt.size);