[binutils-gdb] PR25822, Invalid read in process_symbol_table

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=001890e1f9269697f7e0212430a51479271bdab2

commit 001890e1f9269697f7e0212430a51479271bdab2
Author: Alan Modra <amodra@gmail.com>
Date:   Wed Apr 15 16:38:01 2020 +0930

    PR25822, Invalid read in process_symbol_table
    
            PR 25822
            * readelf.c (get_num_dynamic_syms): Don't set num_of_syms when
            reading buckets or chains fails.

Diff:
---
 binutils/ChangeLog | 6 ++++++
 binutils/readelf.c | 4 +++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index a30d38d4aea..9cac7a2a4ef 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,3 +1,9 @@
+2020-04-15  Alan Modra  <amodra@gmail.com>
+
+	PR 25822
+	* readelf.c (get_num_dynamic_syms): Don't set num_of_syms when
+	reading buckets or chains fails.
+
 2020-04-15  Alan Modra  <amodra@gmail.com>
 
 	* readelf.c (process_symbol_table): Zero gnubuckets, gnuchains
diff --git a/binutils/readelf.c b/binutils/readelf.c
index 80af9a242ac..0ea8273ab11 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -9969,11 +9969,13 @@ get_num_dynamic_syms (Filedata * filedata)
 
       nbuckets = byte_get (nb, hash_ent_size);
       nchains = byte_get (nc, hash_ent_size);
-      num_of_syms = nchains;
 
       buckets = get_dynamic_data (filedata, nbuckets, hash_ent_size);
       chains  = get_dynamic_data (filedata, nchains, hash_ent_size);
 
+      if (buckets != NULL && chains != NULL)
+	num_of_syms = nchains;
+
   no_hash:
       if (num_of_syms == 0)
 	{