On Wed, Nov 01, 2023 at 03:44:01PM +0000, Sam James wrote:
> I thought I'd take a quick look at this. When I tried building with
> -fsanitize=undefined on amd64, unfortunately, I hit another issue
> immediately (with export UBSAN_OPTIONS=print_stacktrace=1:halt_on_error=1)::
>
> util.c:380:3: runtime error: null pointer passed as argument 2, which is
> declared to never be null
> #0 0x5629810d4196 in text_buffer_add_string
> /var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/util.c:380
> #1 0x562981119148 in write_tag_contents
> /var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/scan.c:934
> #2 0x562981119148 in scan_info_tag
> /var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/scan.c:1441
> #3 0x562981119148 in scan_node_contents
> /var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/scan.c:1634
> #4 0x562981110cd2 in info_node_of_tag_ext
> /var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/nodes.c:1289
> #5 0x5629810f34ec in info_indices_of_file_buffer
> /var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/indices.c:161
> #6 0x5629810f6333 in look_in_indices
> /var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/indices.c:514
> #7 0x5629810d7e0c in add_initial_nodes
> /var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/info.c:521
> #8 0x5629810d7e0c in main
> /var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/info.c:1048
> #9 0x7f3996a4b2e6 (/usr/lib64/libc.so.6+0x242e6)
> #10 0x7f3996a4b3a8 in __libc_start_main (/usr/lib64/libc.so.6+0x243a8)
> #11 0x5629810d8e04 in _start
> (/var/tmp/portage/sys-apps/texinfo-7.1/work/texinfo-7.1/info/ginfo+0xde04)
>
> which led to almost every test failing. Trying -fsanitize=alignment
> (which is a subset of =undefined) didn't give me any issues though,
> interestingly. But I didn't try it on other arches yet or poke into the
> matter further.
I think I've fixed this with the following:
diff --git a/ChangeLog b/ChangeLog
index 34596b8f70..1987470ed5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2023-11-04 Gavin Smith <gavinsmith0...@gmail.com>
+
+ * info/scan.c (write_tag_contents): Check if added text is of
+ zero length in order to avoid subsequently calling memcpy with
+ a null source argument. Report with -fsanitize=undefined on amd64
+ from Sam James <s...@gentoo.org>.
+
2023-11-03 Gavin Smith <gavinsmith0...@gmail.com>
* tp/Texinfo/XS/Makefile.am: Make files depend on
diff --git a/info/scan.c b/info/scan.c
index d6183ae9ae..bdf272f9bf 100644
--- a/info/scan.c
+++ b/info/scan.c
@@ -925,11 +925,11 @@ write_extra_bytes_to_output (char *input, long n)
}
/* Like write_extra_bytes_to_output, but writes bytes even when
- preprocess_nodes=Off. */
+ preprocess_nodes=Off. Note n could be 0 for an index tag. */
static void
write_tag_contents (char *input, long n)
{
- if (rewrite_p)
+ if (rewrite_p && n > 0)
{
text_buffer_add_string (&output_buf, input, n);
output_bytes_difference -= n;
