From 68f66feb300423bb9ee5daecb1951af394425a38 Mon Sep 17 00:00:00 2001 From: Stephen Tweedie Date: Fri, 13 May 2005 23:31:19 -0400 Subject: [PATCH] [PATCH] Fix root hole in raw device [Patch] Fix raw device ioctl pass-through Raw character devices are supposed to pass ioctls through to the block devices they are bound to. Unfortunately, they are using the wrong function for this: ioctl_by_bdev(), instead of blkdev_ioctl(). ioctl_by_bdev() performs a set_fs(KERNEL_DS) before calling the ioctl, redirecting the user-space buffer access to the kernel address space. This is, needless to say, a bad thing. This was noticed first on s390, where raw IO was non-functioning. The s390 driver config does not actually allow raw IO to be enabled, which was the first part of the problem. Secondly, the s390 kernel address space is distinct from user, causing legal raw ioctls to fail. I've reproduced this on a kernel built with 4G:4G split on x86, which fails in the same way (-EFAULT if the address does not exist kernel-side; returns success without actually populating the user buffer if it does.) The patch below fixes both the config and address-space problems. It's based closely on a patch by Jan Glauber , which has been tested on s390 at IBM. I've tested it on x86 4G:4G (split address space) and x86_64 (common address space). Kernel-address-space access has been assigned CAN-2005-1264. Signed-off-by: Stephen Tweedie Signed-off-by: Dave Jones Signed-off-by: Greg Kroah-Hartman --- drivers/block/ioctl.c | 2 ++ drivers/char/raw.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/block/ioctl.c b/drivers/block/ioctl.c index 5e03f51..6d7bcc9 100644 --- a/drivers/block/ioctl.c +++ b/drivers/block/ioctl.c @@ -237,3 +237,5 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg) } return ret; } + +EXPORT_SYMBOL_GPL(blkdev_ioctl); diff --git a/drivers/char/raw.c b/drivers/char/raw.c index a2e33ec..131465e 100644 --- a/drivers/char/raw.c +++ b/drivers/char/raw.c @@ -122,7 +122,7 @@ raw_ioctl(struct inode *inode, struct file *filp, { struct block_device *bdev = filp->private_data; - return ioctl_by_bdev(bdev, command, arg); + return blkdev_ioctl(bdev->bd_inode, filp, command, arg); } static void bind_device(struct raw_config_request *rq) -- 1.8.2.3