Messages in this thread Patch in this message | | | Date | Thu, 28 Aug 2003 16:18:53 -0700 | From | Dave Olien <> | Subject | [PATCH] 2.6.0-test4-mm2 drivers/char.c Oops on open() |
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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: - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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