[PATCH] libdw: Make sure end of next cu doesn't overflow section data size.

[PATCH] libdw: Make sure end of next cu doesn't overflow section data size.

[Mark Wielaard]

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An invalid or trucated debug info/type section could cause the cu endp
to point beyond the end of section data.

Signed-off-by: Mark Wielaard <mjw@redhat.com>
---
 libdw/ChangeLog      | 4 ++++
 libdw/libdw_findcu.c | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 8b00970..8d27b8d 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,5 +1,9 @@
 2014-12-11  Mark Wielaard  <mjw@redhat.com>
 
+	* libdw_findcu.c (__libdw_intern_next_unit): Sanity check offset.
+
+2014-12-11  Mark Wielaard  <mjw@redhat.com>
+
 	* dwarf_child.c (__libdw_find_attr): Call __libdw_form_val_len with
 	die->cu->endp, not the abbrev endp.
 	* dwarf_getattrs.c (dwarf_getattrs): Likewise.
diff --git a/libdw/libdw_findcu.c b/libdw/libdw_findcu.c
index 3c9633e..c783ff8 100644
--- a/libdw/libdw_findcu.c
+++ b/libdw/libdw_findcu.c
@@ -94,6 +94,12 @@ __libdw_intern_next_unit (dbg, debug_types)
       return NULL;
     }
 
+  /* Invalid or truncated debug section data?  */
+  Elf_Data *data = dbg->sectiondata[debug_types
+				    ? IDX_debug_types : IDX_debug_info];
+  if (unlikely (*offsetp > data->d_size))
+    *offsetp = data->d_size;
+
   /* Create an entry for this CU.  */
   struct Dwarf_CU *newp = libdw_typed_alloc (dbg, struct Dwarf_CU);
 
-- 
2.1.0

Re: [PATCH] libdw: Make sure end of next cu doesn't overflow section data size.

[Mark Wielaard]

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On Fri, 2014-12-12 at 00:25 +0100, Mark Wielaard wrote:
> An invalid or trucated debug info/type section could cause the cu endp
> to point beyond the end of section data.
>
>  2014-12-11  Mark Wielaard  <mjw@redhat.com>
>  
> +	* libdw_findcu.c (__libdw_intern_next_unit): Sanity check offset.

I pushed this to master.