From: Junfeng Yang <yjf@stanford.edu>
To: Nick Holloway <Nick.Holloway@pyrites.org.uk>
Cc: linux-kernel@vger.kernel.org, <mc@cs.stanford.edu>
Subject: Re: [CHECKER] 30 potential dereference of user-pointer errors
Date: Sun, 27 Apr 2003 14:14:42 -0700 (PDT) [thread overview]
Message-ID: <Pine.GSO.4.44.0304271406180.9838-100000@elaine24.Stanford.EDU> (raw)
In-Reply-To: <20030427201826.DCFCD7D45@bagpuss.pyrites.org.uk>
On Sun, 27 Apr 2003, Nick Holloway wrote:
> In list.linux-kernel yjf@stanford.edu (Junfeng Yang) wrote:
> > [BUG] on VIDIOCGCAPUTRE and VIDIOCSCAPUTRE branches copy_*_user functions are called. on other branches not
> > /home/junfeng/linux-tainted/drivers/media/video/cpia.c:3432:cpia_do_ioctl: ERROR:TAINTED:3432:3432: dereferencing tainted ptr 'vp' [Callstack: ]
> >
> > DBG("VIDIOCSPICT\n");
> >
> > /* check validity */
> > DBG("palette: %d\n", vp->palette);
> > DBG("depth: %d\n", vp->depth);
> >
> > Error --->
> > if (!valid_mode(vp->palette, vp->depth)) {
> > retval = -EINVAL;
> > break;
> > }
> > ---------------------------------------------------------
>
> I can't see this. This code fragment is from cpia_do_ioctl. This is
> never called directly, the entry point is cpia_ioctl, which always passes
> ioctl calls to video_usercopy (which calls cpia_do_ioctl through the
> supplied function pointer).
>
> In video_usercopy, it calls copy_from_user for an _IOW ioctl (which
> VIDIOCSPICT is). There is certainly no differentiation between the
> different ioctl calls made by video_usercopy.
Hi,
Our checker finds an inconsistencies in this function. For case branch
"VIDIOCSCAPTURE" and "VIDIOCGCAPTUER", copy_from_user is called on
argument "arg", which implies arg is a user-pointer. The checker isn't
smart enough to figure out if the dereferences in other branches are
errors or the copy_*_user calls are errors.
I checked videodev.h, where VIDIOCGCAPTURE and VIDIOCSCAPTUER are defined
as _IOR ... and _IOW. does that mean the copy_from_user calls on case
branch VIDIOCGCPAUTER and VIDIOCSCAPUTER are on kernel pointers?
-Junfeng
next prev parent reply other threads:[~2003-04-27 21:02 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-04 11:12 [CHECKER] potential races in kernel/*.c mm/*.c net/*ipv4*.c Dawson Engler
2003-03-04 12:24 ` Hugh Dickins
2003-03-04 13:23 ` Martin Josefsson
2003-03-21 6:33 ` [CHECKER] potential dereference of user pointer errors Junfeng Yang
2003-03-21 21:44 ` Chris Wright
2003-03-21 21:58 ` Junfeng Yang
2003-03-21 22:06 ` Chris Wright
2003-03-21 22:08 ` Junfeng Yang
2003-03-21 22:15 ` Chris Wright
2003-03-22 20:49 ` Alan Cox
2003-03-22 20:19 ` Chris Wright
2003-03-21 23:55 ` Chris Wright
2003-03-27 8:07 ` Jan Kasprzak
2003-03-27 17:10 ` Chris Wright
2003-04-21 7:49 ` [CHECKER] Help Needed! Junfeng Yang
2003-04-21 21:26 ` Chris Wright
2003-04-26 2:18 ` [CHECKER] 30 potential dereference of user-pointer errors Junfeng Yang
2003-04-27 9:26 ` James Morris
2003-04-28 1:55 ` Junfeng Yang
2003-04-27 20:18 ` Nick Holloway
2003-04-27 21:14 ` Junfeng Yang [this message]
2003-04-27 21:29 ` Junfeng Yang
2003-04-28 6:43 ` [CHECKER] 3 potential user-pointer errors in drivers/usb/serial that can print out arbitrary kernel data Junfeng Yang
2003-04-29 7:25 ` Greg KH
2003-04-29 9:14 ` Junfeng Yang
2003-04-28 6:50 ` [CHECKER] 8 potential user-pointer errors that allow arbitrary writes to kernel Junfeng Yang
2003-04-28 12:49 ` Alan Cox
2003-04-28 19:11 ` Junfeng Yang
2003-04-29 0:02 ` [CHECKER] 5 potential user-pointer errors in write_proc Junfeng Yang
2003-04-29 7:26 ` [CHECKER] 30 potential dereference of user-pointer errors Greg KH
2003-03-22 0:15 ` [CHECKER] potential dereference of user pointer errors Chris Wright
2003-03-22 0:32 ` Greg KH
2003-03-22 0:47 ` Chris Wright
2003-03-22 1:00 ` Greg KH
2003-03-22 0:32 ` Chris Wright
2003-03-23 23:10 ` Junfeng Yang
2003-03-24 0:24 ` [CHECKER] 63 potential calling blocking functions with locks held errors Junfeng Yang
2003-03-24 12:35 ` [CHECKER] 8 potential calling blocking kmalloc(GFP_KERNEL) " Junfeng Yang
2003-03-24 0:29 ` [CHECKER] 1 potential double unlock error Junfeng Yang
2003-03-24 9:07 ` [CHECKER] potential dereference of user pointer errors Jaroslav Kysela
2003-03-24 22:28 ` Raja R Harinath
2003-03-25 0:44 ` David S. Miller
2003-03-25 18:52 ` Raja R Harinath
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