libdwfl: add check for elf_memory return value

elf_memory call in __libdw_open_elf_memory can return NULL. It was not
checked and led to the null pointer dereference.

Signed-off-by: Aleksei Vetrov <vvvvvv@google.com>

diff --git a/libdwfl/open.c b/libdwfl/open.c
index b97ff01620add2cb596908435bc2d882ea4e9a6a..d0f357eddcc8ff16fefdcb5e15b88e7910626290 100644 (file)
--- a/libdwfl/open.c
+++ b/libdwfl/open.c
@@ -211,6 +211,10 @@ __libdw_open_elf_memory (char *data, size_t size, Elf **elfp, bool archive_ok)
      won't work.  */
   int fd = -1;
   *elfp = elf_memory (data, size);
+  if (unlikely(*elfp == NULL))
+    {
+      return DWFL_E_LIBELF;
+    }
   /* Allow using this ELF as reference for subsequent elf_begin calls.  */
   (*elfp)->cmd = ELF_C_READ_MMAP_PRIVATE;
   return libdw_open_elf (&fd, elfp, false, archive_ok, true, false, true);

diff --git a/tests/dwfl-report-offline-memory.c b/tests/dwfl-report-offline-memory.c
index e6cb0a51f1c9a42231e84ac040fdb5a049479415..b3b4d9bd167c9e1d1e5bcdd469380e3984269a23 100644 (file)
--- a/tests/dwfl-report-offline-memory.c
+++ b/tests/dwfl-report-offline-memory.c
@@ -77,8 +77,13 @@ main (int argc, char **argv)
   Dwfl *dwfl = dwfl_begin (&offline_callbacks);
   assert (dwfl != NULL);
 
-  Dwfl_Module *mod =
-      dwfl_report_offline_memory (dwfl, argv[1], argv[1], data, size);
+  Dwfl_Module *mod;
+
+  /* Check error handling by suppling zero data */
+  mod = dwfl_report_offline_memory(dwfl, argv[1], argv[1], NULL, 0);
+  assert(mod == NULL);
+
+  mod = dwfl_report_offline_memory(dwfl, argv[1], argv[1], data, size);
   assert (mod != NULL);
   dwfl_report_end (dwfl, NULL, NULL);