[PATCH 3/7] libelf: Check __gelf_getehdr_rdlock call doesn't fail in elf_getdata.

[Mark Wielaard <mark@klomp.org>]

GCC10 -fanalyzer with -flto notices __gelf_getehdr_rdlock can fail
and that the result of the call in __libelf_set_rawdata_wrlock isn't
checked, which can cause a dereference of NULL.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 libelf/ChangeLog     | 5 +++++
 libelf/elf_getdata.c | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index 56f5354c..fcea8aa9 100644
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,3 +1,8 @@
+2020-05-08  Mark Wielaard  <mark@klomp.org>
+
+	* elf_getdata.c (__libelf_set_rawdata_wrlock): Check
+	__gelf_getehdr_rdlock return value.
+
 2020-04-25  Mark Wielaard  <mark@klomp.org>
 
 	* elf_compress.c (__libelf_compress): Remove free (out_buf).
diff --git a/libelf/elf_getdata.c b/libelf/elf_getdata.c
index 40fe1694..0d8f8d2e 100644
--- a/libelf/elf_getdata.c
+++ b/libelf/elf_getdata.c
@@ -271,6 +271,8 @@ __libelf_set_rawdata_wrlock (Elf_Scn *scn)
 	{
 	  GElf_Ehdr ehdr_mem;
 	  GElf_Ehdr *ehdr = __gelf_getehdr_rdlock (elf, &ehdr_mem);
+	  if (unlikely (ehdr == NULL))
+	    return 1;
 	  entsize = SH_ENTSIZE_HASH (ehdr);
 	}
       else
-- 
2.20.1