Re: [CHECKER] 8 potential user-pointer errors that allow arbitrary writes to kernel

From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Junfeng Yang <yjf@stanford.edu>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Chris Wright <chris@wirex.com>,
	mc@cs.stanford.edu
Subject: Re: [CHECKER] 8 potential user-pointer errors that allow arbitrary writes to kernel
Date: 28 Apr 2003 13:49:17 +0100	[thread overview]
Message-ID: <1051534156.16805.13.camel@dhcp22.swansea.linux.org.uk> (raw)
In-Reply-To: <Pine.GSO.4.44.0304272346550.15342-100000@elaine24.Stanford.EDU>

On Llu, 2003-04-28 at 07:50, Junfeng Yang wrote:
> /home/junfeng/linux-tainted/drivers/usb/media/vicam.c:617:vicam_ioctl:
> ERROR:TAINTED:617:617: dereferencing tainted ptr 'vp' [Callstack:
> /home/junfeng/linux-tainted/drivers/scsi/sg.c:1002:vicam_ioctl((tainted
> 3))]
> 
> 			struct video_picture *vp = (struct video_picture
> *) arg;
> 
> 			DBG("VIDIOCSPICT depth = %d, pal = %d\n",
> vp->depth,
> 			    vp->palette);
> 
> 
> Error --->

Correct report. Fixed in 2.4.21-ac now

> /home/junfeng/linux-tainted/drivers/video/sis/sis_main.c:2476:sisfb_ioctl:
> ERROR:TAINTED:2476:2476: dereferencing tainted ptr 'x' [Callstack:
> /home/junfeng/linux-tainted/drivers/video/sstfb.c:808:sisfb_ioctl((tainted
> 3))]
> 

Correct - already fixed in 2.4.21-ac

> ---------------------------------------------------------
> [BUG] can write to anywhere in kernel. do_read is assigned to
> file_operations.read, which can take tainted inputs. even the parm itself
> has a name pUserBuffer
> 
> /home/junfeng/linux-tainted/drivers/isdn/eicon/linchr.c:166:do_read:
> ERROR:TAINTED:166:166: passing tainted ptr 'pClientLogBuffer' to
> __constant_memcpy [Callstack:
> /home/junfeng/linux-tainted/drivers/scsi/sg.c:362:do_read((tainted 1))]
> 
> 
> 	pHeadItem = (klog_t *) DivasLogFifoRead();
> 
Correct - fixed in 2.4.21-ac now

> [BUG] can write to anywhere in kernel. in the same subdir,
> midi_synth.c:midi_synth_ioctl does __copy_to_user(not copy_to_user?). it
> could be that there are some assumptions about the devices.
> 
> /home/junfeng/linux-tainted/sound/oss/mpu401.c:792:mpu_synth_ioctl:
> ERROR:TAINTED:792:792: passing tainted ptr 'arg' to __constant_memcpy
> [Callstack:
> /home/junfeng/linux-tainted/sound/oss/midi_synth.c:270:mpu_synth_ioctl((tainted
> 2))]

The verify is done in soundcard.c
Fixed mpu_synth_ioctl in 2.4.21-ac

> [BUG] can write to anywhere in kernel. mdc800_device_read is assigned to
> file_operations.read, which can take tainted inputs
> 
> /home/junfeng/linux-tainted/drivers/usb/image/mdc800.c:750:mdc800_device_read:
> ERROR:TAINTED:750:750: passing tainted ptr 'ptr' to __memcpy [Callstack:
> /home/junfeng/linux-tainted/drivers/scsi/sg.c:362:mdc800_device_read((tainted
> 1))]

Correct. Fixed in 2.4.21-ac

> [BUG] can write to anywhere in kernel. file_operations.write
> 
> /home/junfeng/linux-tainted/drivers/usb/image/mdc800.c:805:mdc800_device_write:
> ERROR:TAINTED:805:805: dereferencing tainted ptr 'buf + i' [Callstack:
> /home/junfeng/linux-tainted/drivers/media/dvb/av7110/av7110.c:3858:mdc800_device_write((tainted
> 1))]

Correct, fixed in 2.4.21-ac

> [BUG] can write to anywhere in kernel. awe_ioctl is assigned to
> file_operations.ioctl
> 
> /home/junfeng/linux-tainted/sound/oss/awe_wave.c:2049:awe_ioctl:
> ERROR:TAINTED:2049:2049: passing tainted ptr 'arg' to __constant_memcpy
> [Callstack:
> /home/junfeng/linux-tainted/sound/oss/midi_synth.c:270:awe_ioctl((tainted
> 2))]
> 
> 	case SNDCTL_SYNTH_INFO:
> 		if (playing_mode == AWE_PLAY_DIRECT)
> 			awe_info.nr_voices = awe_max_voices;
> 		else
> 			awe_info.nr_voices = AWE_MAX_CHANNELS;
> 
> Error --->
> 		memcpy((char*)arg, &awe_info, sizeof(awe_info));

Already fixed in 2.4, but correct report