Messages in this thread Patch in this message | | | Date | Thu, 29 Oct 2009 09:34:16 +0100 | From | Heiko Carstens <> | Subject | Re: is avoiding compat ioctls possible? |
| |
On Wed, Oct 28, 2009 at 10:41:57PM -0700, David Miller wrote: > From: Arnd Bergmann <arndbergmann@googlemail.com> > Date: Wed, 28 Oct 2009 16:40:18 +0100 > > > I'm pretty sure it was ok when we started adding the compat_ioctl > > handlers years ago. I think most people just ignored these for > > the majority of drivers that can't possibly run on s390. Even > > on s390, gcc will always do the right thing if you call call ioctl > > with a pointer to a normal object in the .data section, heap or stack, > > but hand-written assembly or other compilers may not. > > Arnd, even compat_sys_ioctl() itself has constructs like: > > case FS_IOC_RESVSP: > case FS_IOC_RESVSP64: > error = ioctl_preallocate(filp, (void __user *)arg); > goto out_fput;
That's broken, but it's quite new code. In general it looks like we don't have many compat ioctl problems on s390. At least I don't remember when we faced the last bug. We did have some compat syscall issues when SLES11 testing started. The lack of bug reports is probably just a lack of 32 bit userspace ;)
This should fix at least the bug above:
Subject: [PATCH] fs: add missing compat_ptr handling for FS_IOC_RESVSP ioctl
From: Heiko Carstens <heiko.carstens@de.ibm.com>
For FS_IOC_RESVSP and FS_IOC_RESVSP64 compat_sys_ioctl() uses its arg argument as a pointer to userspace. However it is missing a a call to compat_ptr() which will do a proper pointer conversion.
This was introduced with 3e63cbb1 "fs: Add new pre-allocation ioctls to vfs for compatibility with legacy xfs ioctls".
Cc: Ankit Jain <me@ankitjain.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Arnd Bergmann <arndbergmann@googlemail.com> Reported-by: David Miller <davem@davemloft.net> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> --- fs/compat_ioctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c index f91fd51..d84e705 100644 --- a/fs/compat_ioctl.c +++ b/fs/compat_ioctl.c @@ -1800,7 +1800,7 @@ struct space_resv_32 { /* just account for different alignment */ static int compat_ioctl_preallocate(struct file *file, unsigned long arg) { - struct space_resv_32 __user *p32 = (void __user *)arg; + struct space_resv_32 __user *p32 = compat_ptr(arg); struct space_resv __user *p = compat_alloc_user_space(sizeof(*p)); if (copy_in_user(&p->l_type, &p32->l_type, sizeof(s16)) || @@ -2802,7 +2802,7 @@ asmlinkage long compat_sys_ioctl(unsigned int fd, unsigned int cmd, #else case FS_IOC_RESVSP: case FS_IOC_RESVSP64: - error = ioctl_preallocate(filp, (void __user *)arg); + error = ioctl_preallocate(filp, compat_ptr(arg)); goto out_fput; #endif
| |