* [PATCH] 2.6.0-test4-mm2 drivers/char.c Oops on open()
@ 2003-08-28 23:18 Dave Olien
2003-08-28 23:22 ` [PATCH] 2.6.0-test4-mm2 drivers/char.c ---> drivers/char/raw.c Dave Olien
0 siblings, 1 reply; 2+ messages in thread
From: Dave Olien @ 2003-08-28 23:18 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel
The raw.c character device Oopses dereferencing a NULL pointer in bd_claim()
This problem occurred after bd_claim() in block_dev.c was modified to "claim
the whole device when a partition is claimed".
raw_open() made the mistake of calling bd_claim BEFORE calling
blkdev_get(). At that time, the bdev->bd_contains field. has't been
initialized yet. Switching the order allows blkdev_get() to initialize
those fields before calling bd_claim().
Also fixed up some error return paths:
igrab() should never fail under these circumstances since the caller
already has a reference to that inode through the bdev at that time.
In the event of blkdev_get() failure or set_blocksize() failure, not
all the work to unwind from the error was done.
--- linux-2.6.0-test4-mm2_original/drivers/char/raw.c 2003-08-28 13:16:03.000000000 -0700
+++ linux-2.6.0-test4-mm2_raw/drivers/char/raw.c 2003-08-28 14:07:44.000000000 -0700
@@ -60,25 +60,25 @@
bdev = raw_devices[minor].binding;
err = -ENODEV;
if (bdev) {
- err = bd_claim(bdev, raw_open);
+ err = blkdev_get(bdev, filp->f_mode, 0, BDEV_RAW);
if (err)
goto out;
- err = -ENODEV;
- if (!igrab(bdev->bd_inode))
+ igrab(bdev->bd_inode);
+ err = bd_claim(bdev, raw_open);
+ if (err) {
+ blkdev_put(bdev, BDEV_RAW);
goto out;
- err = blkdev_get(bdev, filp->f_mode, 0, BDEV_RAW);
+ }
+ err = set_blocksize(bdev, bdev_hardsect_size(bdev));
if (err) {
bd_release(bdev);
+ blkdev_put(bdev, BDEV_RAW);
goto out;
- } else {
- err = set_blocksize(bdev, bdev_hardsect_size(bdev));
- if (err == 0) {
- filp->f_flags |= O_DIRECT;
- if (++raw_devices[minor].inuse == 1)
- filp->f_dentry->d_inode->i_mapping =
- bdev->bd_inode->i_mapping;
- }
}
+ filp->f_flags |= O_DIRECT;
+ if (++raw_devices[minor].inuse == 1)
+ filp->f_dentry->d_inode->i_mapping =
+ bdev->bd_inode->i_mapping;
}
filp->private_data = bdev;
out:
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] 2.6.0-test4-mm2 drivers/char.c ---> drivers/char/raw.c
2003-08-28 23:18 [PATCH] 2.6.0-test4-mm2 drivers/char.c Oops on open() Dave Olien
@ 2003-08-28 23:22 ` Dave Olien
0 siblings, 0 replies; 2+ messages in thread
From: Dave Olien @ 2003-08-28 23:22 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel
Mistake in subject line... should refer to drivers/char/raw.c
On Thu, Aug 28, 2003 at 04:18:53PM -0700, Dave Olien wrote:
>
> The raw.c character device Oopses dereferencing a NULL pointer in bd_claim()
> This problem occurred after bd_claim() in block_dev.c was modified to "claim
> the whole device when a partition is claimed".
>
> raw_open() made the mistake of calling bd_claim BEFORE calling
> blkdev_get(). At that time, the bdev->bd_contains field. has't been
> initialized yet. Switching the order allows blkdev_get() to initialize
> those fields before calling bd_claim().
>
> Also fixed up some error return paths:
>
> igrab() should never fail under these circumstances since the caller
> already has a reference to that inode through the bdev at that time.
>
> In the event of blkdev_get() failure or set_blocksize() failure, not
> all the work to unwind from the error was done.
>
> --- linux-2.6.0-test4-mm2_original/drivers/char/raw.c 2003-08-28 13:16:03.000000000 -0700
> +++ linux-2.6.0-test4-mm2_raw/drivers/char/raw.c 2003-08-28 14:07:44.000000000 -0700
> @@ -60,25 +60,25 @@
> bdev = raw_devices[minor].binding;
> err = -ENODEV;
> if (bdev) {
> - err = bd_claim(bdev, raw_open);
> + err = blkdev_get(bdev, filp->f_mode, 0, BDEV_RAW);
> if (err)
> goto out;
> - err = -ENODEV;
> - if (!igrab(bdev->bd_inode))
> + igrab(bdev->bd_inode);
> + err = bd_claim(bdev, raw_open);
> + if (err) {
> + blkdev_put(bdev, BDEV_RAW);
> goto out;
> - err = blkdev_get(bdev, filp->f_mode, 0, BDEV_RAW);
> + }
> + err = set_blocksize(bdev, bdev_hardsect_size(bdev));
> if (err) {
> bd_release(bdev);
> + blkdev_put(bdev, BDEV_RAW);
> goto out;
> - } else {
> - err = set_blocksize(bdev, bdev_hardsect_size(bdev));
> - if (err == 0) {
> - filp->f_flags |= O_DIRECT;
> - if (++raw_devices[minor].inuse == 1)
> - filp->f_dentry->d_inode->i_mapping =
> - bdev->bd_inode->i_mapping;
> - }
> }
> + filp->f_flags |= O_DIRECT;
> + if (++raw_devices[minor].inuse == 1)
> + filp->f_dentry->d_inode->i_mapping =
> + bdev->bd_inode->i_mapping;
> }
> filp->private_data = bdev;
> out:
^ permalink raw reply [flat|nested] 2+ messages in thread
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2003-08-28 23:18 [PATCH] 2.6.0-test4-mm2 drivers/char.c Oops on open() Dave Olien
2003-08-28 23:22 ` [PATCH] 2.6.0-test4-mm2 drivers/char.c ---> drivers/char/raw.c Dave Olien
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