[PATCH] readelf: Check count fits and doesn't overflow fptr in handle_file_note.

[Mark Wielaard]

Signed-off-by: Mark Wielaard <m...@redhat.com>
---
 src/ChangeLog | 5 +++++
 src/readelf.c | 8 ++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/ChangeLog b/src/ChangeLog
index 4771dc9..456e5a4 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2014-12-09  Mark Wielaard  <m...@redhat.com>
+
+       * readelf.c (handle_file_note): Check count fits data section and
+       doesn't overflow fptr.
+
 2014-12-08  Mark Wielaard  <m...@redhat.com>
 
        * readelf.c (print_debug_exception_table): Report invalid data if
diff --git a/src/readelf.c b/src/readelf.c
index 1db54c6..c6d10f7 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -9017,9 +9017,13 @@ handle_file_note (Elf *core, GElf_Word descsz, GElf_Off 
desc_pos)
       return;
     }
 
+  size_t addrsize = gelf_fsize (core, ELF_T_ADDR, 1, EV_CURRENT);
+  uint64_t maxcount = (size_t) (end - ptr) / (3 * addrsize);
+  if (count > maxcount)
+    goto fail;
+
   /* Where file names are stored.  */
-  unsigned char const *const fstart
-    = ptr + 3 * count * gelf_fsize (core, ELF_T_ADDR, 1, EV_CURRENT);
+  unsigned char const *const fstart = ptr + 3 * count * addrsize;
   char const *fptr = (char *) fstart;
 
   printf ("    %" PRId64 " files:\n", count);
-- 
1.8.3.1