On Wed, 31 Dec 2008 18:08:02 +0900 FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> wrote:
> On Tue, 30 Dec 2008 15:46:03 -0800
> Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> > On Sun, 28 Dec 2008 17:50:35 +0300
> > Alexey Zaytsev <alexey.zaytsev@xxxxxxxxx> wrote:
> >
> > > sizeof(unsigned (short)) is actually sizeof(function), == 1.
> > > Spotted by sparse.
> > >
> > > Signed-off-by: Alexey Zaytsev <alexey.zaytsev@xxxxxxxxx>
> > > ---
> > > fs/compat_ioctl.c | 2 +-
> > > 1 files changed, 1 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
> > > index 5235c67..7c2d617 100644
> > > --- a/fs/compat_ioctl.c
> > > +++ b/fs/compat_ioctl.c
> > > @@ -784,7 +784,7 @@ static int sg_ioctl_trans(unsigned int fd, unsigned int cmd, unsigned long arg)
> > >
> > > if (copy_in_user(&sgio->status, &sgio32->status,
> > > (4 * sizeof(unsigned char)) +
> > > - (2 * sizeof(unsigned (short))) +
> > > + (2 * sizeof(unsigned short)) +
> > > (3 * sizeof(int))))
> > > return -EFAULT;
> >
> > gack.
> >
> > akpm:/home/akpm> cat t.c
> > main()
> > {
> > printf("%d\n", sizeof(unsigned (short)));
> > printf("%d\n", sizeof(unsigned short));
> > }
> > akpm:/home/akpm> ./a.out
> > 1
> > 2
> >
> >
> > the code has been like this for years and years. Why hasn't anyone
> > noticed?
>
> The members from 'status' in struct sg_io_hdr to the last are used to
> transfer information from kernel to user space. The values that user
> space sets are just ignored.
OK.
> typedef struct sg_io_hdr
> {
> int interface_id; /* [i] 'S' for SCSI generic (required) */
> int dxfer_direction; /* [i] data transfer direction */
> unsigned char cmd_len; /* [i] SCSI command length ( <= 16 bytes) */
> unsigned char mx_sb_len; /* [i] max length to write to sbp */
> unsigned short iovec_count; /* [i] 0 implies no scatter gather */
> unsigned int dxfer_len; /* [i] byte count of data transfer */
> void __user *dxferp; /* [i], [*io] points to data transfer memory
> or scatter gather list */
> unsigned char __user *cmdp; /* [i], [*i] points to command to perform */
> void __user *sbp; /* [i], [*o] points to sense_buffer memory */
> unsigned int timeout; /* [i] MAX_UINT->no timeout (unit: millisec) */
> unsigned int flags; /* [i] 0 -> default, see SG_FLAG... */
> int pack_id; /* [i->o] unused internally (normally) */
> void __user * usr_ptr; /* [i->o] unused internally */
> unsigned char status; /* [o] scsi status */
> unsigned char masked_status;/* [o] shifted, masked scsi status */
> unsigned char msg_status; /* [o] messaging level data (optional) */
> unsigned char sb_len_wr; /* [o] byte count actually written to sbp */
> unsigned short host_status; /* [o] errors from host adapter */
> unsigned short driver_status;/* [o] errors from software driver */
> int resid; /* [o] dxfer_len - actual_transferred */
> unsigned int duration; /* [o] time taken by cmd (unit: millisec) */
> unsigned int info; /* [o] auxiliary information */
> } sg_io_hdr_t; /* 64 bytes long (on i386) */
So if for some reason the kernel doesn't write to .info, we'll leak two
bytes of kernel memory.
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