On Wed, 2009-06-03 at 10:01 +0800, Figo.zhang wrote:
> add poiter check for videobuf_queue_core_init().
>
> any guys who write a v4l driver, pass a NULL pointer or a non-inintial
> pointer to the first parameter such as videobuf_queue_sg_init() , it
> would be crashed.
>
> Signed-off-by: Figo.zhang <figo1802@xxxxxxxxx>
> ---
> drivers/media/video/videobuf-core.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c
> index b7b0584..5f41fd9 100644
> --- a/drivers/media/video/videobuf-core.c
> +++ b/drivers/media/video/videobuf-core.c
> @@ -118,6 +118,7 @@ void videobuf_queue_core_init(struct videobuf_queue *q,
> void *priv,
> struct videobuf_qtype_ops *int_ops)
> {
> + BUG_ON(!q);
> memset(q, 0, sizeof(*q));
> q->irqlock = irqlock;
> q->dev = dev;
>
i do a test driver for it, the main code like this.
struct mydev_dev{
struct video_device *video_dev;
...
struct videobuf_queue *cap;
};
static int video_open(struct inode *inode, struct file *file)
{
...
videobuf_queue_dma_contig_init(dev->cap, &video_qops,
&dev->pci->dev, &dev->slock,
V4L2_BUF_TYPE_VIDEO_CAPTURE,
V4L2_FIELD_ALTERNATE,
sizeof(struct mydev_buf),
dev);
...
}
i pass a non-initial pointer for the first argment, so it crashed.
BUG: unable to handle kernel NULL pointer dereference at 00000000
IP: [<f8d6bd67>] :videobuf_core:videobuf_queue_core_init+0x1b/0xbf
*pde = 7ed5a067
Oops: 0002 [#1] SMP
Modules linked in: mydev_drv tvp5160_vd videobuf_dma_contig videobuf_dma_sg
videobuf_core videocodec videodev v4l2_int_device v4l2_common v4l1_compat
compat_ioctl32 fuse i915 drm sco bridge stp bnep l2cap bluetooth sunrpc ipv6
cpufreq_ondemand acpi_cpufreq dm_multipath uinput snd_hda_intel snd_seq_dummy
snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device ppdev snd_pcm_oss parport_pc
snd_mixer_oss snd_pcm snd_timer snd_page_alloc snd_hwdep parport snd i2c_i801
i2c_core pcspkr soundcore iTCO_wdt iTCO_vendor_support r8169 mii ftdi_sio usbserial
ata_generic pata_acpi [last unloaded: microcode]
Pid: 4053, comm: capture Not tainted (2.6.27.5-117.fc10.i686 #1)
EIP: 0060:[<f8d6bd67>] EFLAGS: 00210246 CPU: 1
EIP is at videobuf_queue_core_init+0x1b/0xbf [videobuf_core]
EAX: 00000000 EBX: 00000000 ECX: 00000036 EDX: 00000036
ESI: f8e1e158 EDI: 00000000 EBP: f15f3e28 ESP: f15f3e18
DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process capture (pid: 4053, ti=f15f3000 task=f1550000 task.ti=f15f3000)
Stack: f790905c f5fd5224 f15d8840 f5811560 f15f3e48 f8e01163 f5fd5224 00000001
00000007 0000006c f5fd5200 f8e0202c f15f3e70 f8e1b5a0 f5fd5224 00000001
00000007 0000006c f5fd5200 f8e0faa4 00000000 f15d8840 f15f3e88 f8e0c195
Call Trace:
[<f8e01163>] ? videobuf_queue_dma_contig_init+0x1c/0x21 [videobuf_dma_contig]
[<f8e1b5a0>] ? video_open+0x8b/0xb1 [kt2741drv]
[<f8e0c195>] ? video_open+0xc7/0x125 [videodev]
[<c0492767>] ? chrdev_open+0x12b/0x142
[<c048edd2>] ? __dentry_open+0x10e/0x1fc
[<c048ef47>] ? nameidata_to_filp+0x1f/0x33
[<c049263c>] ? chrdev_open+0x0/0x142
[<c0498a3c>] ? do_filp_open+0x31c/0x611
[<c048a971>] ? virt_to_head_page+0x22/0x2e
[<c041d8ba>] ? need_resched+0x18/0x22
[<c048ebf0>] ? do_sys_open+0x42/0xb7
[<c048eca7>] ? sys_open+0x1e/0x26
[<c0403c76>] ? syscall_call+0x7/0xb
[<c06a007b>] ? init_intel_cacheinfo+0x0/0x421
=======================
Code: d8 e8 69 ff ff ff 89 d8 e8 6d a9 93 c7 5b 5d c3 55 89 e5 57 89 c7 56 89
d6 53 ba 36 00 00 00 83 ec 04 89 c3 89 4d f0 31 c0 89 d1 <f3> ab 8b 45 08 8b
4d f0 89 b3 b8 00 00 00 89 43 10 8b 45 0c 89
EIP: [<f8d6bd67>] videobuf_queue_core_init+0x1b/0xbf [videobuf_core] SS:ESP 0068:f15f3e18
---[ end trace 4bfe52d17b82af8c ]---
so i think it need to add pointer checking for the first argment of videobuf_queue_core_init(),
the videobuf code would be more stronger and reliable.
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