binfmt_elf: fix corner case kfree of uninitialized data

If elf_core_dump() is called and fill_note_info() fails in the kmalloc()
then it returns 0 but has not yet initialised all the needed fields.  As a
result we do a kfree(randomness) after correctly skipping the thread data.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/binfmt_elf.c

@@ -1601,8 +1601,10 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 	info->thread = NULL;
 
 	psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
-	if (psinfo == NULL)
+	if (psinfo == NULL) {
+		info->psinfo.data = NULL; /* So we don't free this wrongly */
 		return 0;
+	}
 
 	fill_note(&info->psinfo, "CORE", NT_PRPSINFO, sizeof(*psinfo), psinfo);