From: Al Viro <viro@ftp.linux.org.uk>
To: Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: filldir[64] oddness
Date: Thu, 9 Mar 2006 04:38:02 +0000 [thread overview]
Message-ID: <20060309043802.GR27946@ftp.linux.org.uk> (raw)
In-Reply-To: <20060309042744.GA23148@redhat.com>
On Wed, Mar 08, 2006 at 11:27:44PM -0500, Dave Jones wrote:
> I'm puzzled by an aparent use of uninitialised memory
> that coverity's checker picked up.
>
> fs/readdir.c
>
> #define NAME_OFFSET(de) ((int) ((de)->d_name - (char __user *) (de)))
> #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
>
> 140 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
> 141 ino_t ino, unsigned int d_type)
> 142 {
> 143 struct linux_dirent __user * dirent;
> 144 struct getdents_callback * buf = (struct getdents_callback *) __buf
> 145 int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 2);
>
> How come that NAME_OFFSET isn't causing an oops when
> it dereferences stackjunk->d_name ?
It doesn't dereference it. d_name is an array, not a pointer. FWIW,
it should've been
#define NAME_OFFSET(de) offsetof(typeof(de), d_name)
or, better yet
#define NAME_OFFSET offsetof(struct linux_dirent, d_name)
#define NAME_OFFSET64 offsetof(struct linux_dirent64, d_name)
prev parent reply other threads:[~2006-03-09 4:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-09 4:27 filldir[64] oddness Dave Jones
2006-03-09 4:32 ` David S. Miller
2006-03-09 4:38 ` Dave Jones
2006-03-09 4:40 ` Al Viro
2006-03-09 17:02 ` Bryan O'Sullivan
2006-03-09 17:07 ` Dave Jones
2006-03-09 17:15 ` Bryan O'Sullivan
2006-03-09 17:27 ` Dave Jones
2006-03-10 1:41 ` Kyle Moffett
2006-03-10 1:44 ` Al Viro
2006-03-09 4:33 ` Vadim Lobanov
2006-03-09 4:34 ` Stephen Rothwell
2006-03-09 4:38 ` Al Viro [this message]
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