libdwfl: Make sure there is at least one phdr

The buffer read in needs to contain room for at least one Phdr.

Signed-off-by: Mark Wielaard <mark@klomp.org>

2 files changed, 9 insertions, 0 deletions

diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index d4eee639..8760b1ef 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,5 +1,9 @@
 2021-12-16  Mark Wielaard  <mark@klomp.org>
 
+        * link_map.c (dwfl_link_map_report): Make sure phnum is non-zero.
+
+2021-12-16  Mark Wielaard  <mark@klomp.org>
+
         * link_map.c (dwfl_link_map_report): Make sure dyn_filesz / entsize is
         non-zero.
 
diff --git a/libdwfl/link_map.c b/libdwfl/link_map.c
index 177ad9a5..c4f79f11 100644
--- a/libdwfl/link_map.c
+++ b/libdwfl/link_map.c
@@ -890,6 +890,11 @@ dwfl_link_map_report (Dwfl *dwfl, const void *auxv, size_t auxv_size,
                 {
                   nbytes = in.d_size;
                   phnum = nbytes / phent;
+                  if (phnum == 0)
+                    {
+                      __libdwfl_seterrno (DWFL_E_BADELF);
+                      return false;
+                    }
                 }
               void *buf = malloc (nbytes);
               Elf32_Phdr (*p32)[phnum] = buf;