[PATCH] readelf: Return correct readp (or readendp) from print_form_data.

[PATCH] readelf: Return correct readp (or readendp) from print_form_data.

[Mark Wielaard]

print_form_data returns the new readp (or readendp on error) to show how
much data was consumed. But when reading the .debug_str_offsets section
we would reuse readp and readendp. This meant the wrong readp would be
returned to the caller.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 src/ChangeLog |  5 +++++
 src/readelf.c | 10 +++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/ChangeLog b/src/ChangeLog
index 6484b9a..fd45405 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2018-06-11  Mark Wielaard  <mark@klomp.org>
+
+	* readelf.c (print_form_data): Don't reuse readp and readendp when
+	reading str_offsets section.
+
 2018-06-10  Mark Wielaard  <mark@klomp.org>
 
 	* readelf.c (print_form_data): Don't cast value to ptrdiff_t, cast
diff --git a/src/readelf.c b/src/readelf.c
index fbda6c1..f185897 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -7986,17 +7986,17 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp,
 	str = "???";
       else
 	{
-	  readp = data->d_buf + str_offsets_base + val;
-	  readendp = data->d_buf + data->d_size;
-	  if ((size_t) (readendp - readp) < offset_len)
+	  const unsigned char *strreadp = data->d_buf + str_offsets_base + val;
+	  const unsigned char *strreadendp = data->d_buf + data->d_size;
+	  if ((size_t) (strreadendp - strreadp) < offset_len)
 	    str = "???";
 	  else
 	    {
 	      Dwarf_Off idx;
 	      if (offset_len == 8)
-		idx = read_8ubyte_unaligned_inc (dbg, readp);
+		idx = read_8ubyte_unaligned_inc (dbg, strreadp);
 	      else
-		idx = read_4ubyte_unaligned_inc (dbg, readp);
+		idx = read_4ubyte_unaligned_inc (dbg, strreadp);
 
 	      data = dbg->sectiondata[IDX_debug_str];
 	      if (data == NULL || idx >= data->d_size
-- 
1.8.3.1

Re: [PATCH] readelf: Return correct readp (or readendp) from print_form_data.

[Mark Wielaard]

On Mon, Jun 11, 2018 at 11:33:14AM +0200, Mark Wielaard wrote:
> print_form_data returns the new readp (or readendp on error) to show how
> much data was consumed. But when reading the .debug_str_offsets section
> we would reuse readp and readendp. This meant the wrong readp would be
> returned to the caller.

Pushed to master.