Re: Possible segfault introduced in commit.c

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


Am 25.04.2012 13:14, schrieb Jeff King:
On Wed, Apr 25, 2012 at 12:59:28AM -0700, Michael Mueller wrote:

As you might already know, we analyze git regularly with Sentry (our
static analysis tool).  Today it picked up a new NULL pointer
dereference in commit.c:366:

     void commit_list_reverse(struct commit_list **list_p)
     {
         struct commit_list *prev = NULL, *curr = *list_p, *next;

         if (!list_p)
             return;
         /* function continues... */
     }

list_p is dereferenced on the first line, then tested for NULL on
the very next statement.  If it's possible that list_p is NULL, this
will be a segfault.  If it can't be NULL, then the check is
unnecessary (and probably misleading).

Yes, you're right. There is only one caller currently, and it can never
be NULL (it passes the address-of a pointer variable). I think dropping
the NULL-check is the right thing; even an empty list will still have a
pointer to its NULL head.

More often then not, a mistake like that is surrounded by other issues. No, I didn't put it there intentionally to prove this point. ;-)

Having to reverse the list at all is unfortunate and I only did that because I thought appending would be more complicated and because we are going to replace the linked list with a different data structure soon anyway. Turns out appending is easy. Patches to follow.

René
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Newbies FAQ]     [Linux Kernel Development]     [Free Online Dating]     [Gcc Help]     [IETF Annouce]     [DCCP]     [Netdev]     [Networking]     [Security]     [V4L]     [Bugtraq]     [Free Online Dating]     [Photo]     [Yosemite]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux SCSI]     [Fedora Users]     [Linux Resources]

Add to Google