From 072cebc2c736bec33e90299b49d82976c12b5549 Mon Sep 17 00:00:00 2001

From: Shawn Landden <shawn@churchofgit.com>

Date: Mon, 16 Dec 2013 15:41:00 -0800

Subject: [PATCH] journal: fix against (theoretical) undefined behavior

While all the libc implementations I know return NULL when memchr's size

parameter is 0, without accessing any memory, passing NULL to memchr is

still invalid:

C11 7.24.1p2: Where an argument declared as "size_t n" specifies the length

of the array for a function, n can have the value zero on a call to that

function. Unless explicitly stated otherwise in the description of a

particular function in this subclause, pointer arguments on such a call

shall still have valid values, as described in 7.1.4. On such a call, a

function that locates a character finds no occurrence, a function that

compares two character sequences returns zero, and a function that copies

characters copies zero characters.

see http://llvm.org/bugs/show_bug.cgi?id=18247

---

 src/journal/journal-file.c | 5 ++++-

 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c

index ebf72f3..2c0fd0c 100644

--- a/src/journal/journal-file.c

+++ b/src/journal/journal-file.c

@@ -1010,7 +1010,10 @@ static int journal_file_append_data(

         if (r < 0)

                 return r;

-        eq = memchr(data, '=', size);

+        if (!data)

+                eq = NULL;

+        else

+                eq = memchr(data, '=', size);

         if (eq && eq > data) {

                 uint64_t fp;

                 Object *fo;