BLKGETSIZE64 is broken (0x80041272)

BLKGETSIZE64 is broken (0x80041272)

[Pete Zaitcev]

I was adding ioctl translations and found that BLKGETSIZE64
equals 0x80041272, with wrong size. Apparently, a whole bunch
of ioctls takes sizeof(sizeof(foo)), which evaluates to 4
in 32 bit userland, regardless of the size of foo.
Are we going to do anything about it? At the bare minimum,
I suggest we add comments near EVERY of the offenders,
marking them as broken and warning that we are leaving them
as is for binary compatibility. I compared 2.4 and 2.5, and
the same breakage is present in both, only more people fell
for this trap in 2.5, so it obviously needs some action.

-- Pete

[zaitcev@niphredil linux-2.5.64-sparc]$ grep _IOR include/linux/*.h | grep sizeof
include/linux/fs.h:#define BLKELVGET  _IOR(0x12,106,sizeof(blkelv_ioctl_arg_t))/* elevator get */
include/linux/fs.h:#define BLKBSZGET  _IOR(0x12,112,sizeof(int))
include/linux/fs.h:#define BLKGETSIZE64 _IOR(0x12,114,sizeof(u64))      /* return device size in bytes (u64 *arg) */
include/linux/i8k.h:#define I8K_POWER_STATUS    _IOR ('i', 0x82, sizeof(int))
include/linux/i8k.h:#define I8K_FN_STATUS               _IOR ('i', 0x83, sizeof(int))
include/linux/i8k.h:#define I8K_GET_TEMP                _IOR ('i', 0x84, sizeof(int))
include/linux/matroxfb.h:#define MATROXFB_GET_OUTPUT_CONNECTION _IOR('n',0xF8,sizeof(__u32))
include/linux/matroxfb.h:#define MATROXFB_GET_AVAILABLE_OUTPUTS _IOR('n',0xF9,sizeof(__u32))
include/linux/matroxfb.h:#define MATROXFB_GET_ALL_OUTPUTS       _IOR('n',0xFB,sizeof(__u32))
include/linux/pmu.h:#define PMU_IOC_GET_BACKLIGHT       _IOR('B', 1, sizeof(__u32*))
include/linux/pmu.h:#define PMU_IOC_GET_MODEL   _IOR('B', 3, sizeof(__u32*))
include/linux/pmu.h:#define PMU_IOC_HAS_ADB             _IOR('B', 4, sizeof(__u32*))
include/linux/pmu.h:#define PMU_IOC_CAN_SLEEP   _IOR('B', 5, sizeof(__u32*))
include/linux/radeonfb.h:#define FBIO_RADEON_GET_MIRROR _IOR('@', 3, sizeof(__u32*))
include/linux/sisfb.h:#define SISFB_GET_INFO      _IOR('n',0xF8,sizeof(__u32))
[zaitcev@niphredil linux-2.5.64-sparc]$

-- Pete

Re: BLKGETSIZE64 is broken (0x80041272)

[Anton Blanchard]

> I was adding ioctl translations and found that BLKGETSIZE64
> equals 0x80041272, with wrong size. Apparently, a whole bunch
> of ioctls takes sizeof(sizeof(foo)), which evaluates to 4
> in 32 bit userland, regardless of the size of foo.
> Are we going to do anything about it? At the bare minimum,
> I suggest we add comments near EVERY of the offenders,
> marking them as broken and warning that we are leaving them
> as is for binary compatibility. I compared 2.4 and 2.5, and
> the same breakage is present in both, only more people fell
> for this trap in 2.5, so it obviously needs some action.

Thats old news :) Check out ppc64 and sparc64 ioctl32.c, its ugly but we
have to translate them.

Anton

Re: BLKGETSIZE64 is broken (0x80041272)

[David S. Miller]

On Thu, 2003-03-27 at 18:42, Pete Zaitcev wrote:
> I was adding ioctl translations and found that BLKGETSIZE64
> equals 0x80041272, with wrong size. Apparently, a whole bunch
> of ioctls takes sizeof(sizeof(foo)), which evaluates to 4
> in 32 bit userland, regardless of the size of foo.
> Are we going to do anything about it?

Anton and I noticed this a few months ago, we just handle it
the way it needs to be in the ioctl32 translation layers of
ppc64 and sparc64.  I believe we even notified people such
as Andi Kleen at the time this was discovered by Anton.

-- 
David S. Miller <davem@redhat.com>