Re: [PATCH 5.5 284/367] compat: scsi: sg: fix v3 compat read/write interface

[Naresh Kamboju <naresh.kamboju@linaro.org>]

The arm64 architecture 64k page size enabled build failed on stable rc 5.5
CONFIG_ARM64_64K_PAGES=y
CROSS_COMPILE=aarch64-linux-gnu-
Toolchain gcc-9

In file included from ../block/scsi_ioctl.c:23:
 ../include/scsi/sg.h:75:2: error: unknown type name ‘compat_int_t’
  compat_int_t interface_id; /* [i] 'S' for SCSI generic (required) */
  ^~~~~~~~~~~~
 ../include/scsi/sg.h:76:2: error: unknown type name ‘compat_int_t’
  compat_int_t dxfer_direction; /* [i] data transfer direction  */
  ^~~~~~~~~~~~

...
 ../include/scsi/sg.h:97:2: error: unknown type name ‘compat_uint_t’
  compat_uint_t info;  /* [o] auxiliary information */
  ^~~~~~~~~~~~~
 make[2]: *** [../scripts/Makefile.build:266: block/bsg.o] Error

Ref:
https://gitlab.com/Linaro/lkft/kernel-runs/-/jobs/431659186

On Mon, 10 Feb 2020 at 18:18, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> commit 78ed001d9e7106171e0ee761cd854137dd731302 upstream.
>
> In the v5.4 merge window, a cleanup patch from Al Viro conflicted
> with my rework of the compat handling for sg.c read(). Linus Torvalds
> did a correct merge but pointed out that the resulting code is still
> unsatisfactory.
>
> I later noticed that the sg_new_read() function still gets the compat
> mode wrong, when the 'count' argument is large enough to pass a
> compat_sg_io_hdr object, but not a nativ sg_io_hdr.
>
> To address both of these, move the definition of compat_sg_io_hdr
> into a scsi/sg.h to make it visible to sg.c and rewrite the logic
> for reading req_pack_id as well as the size check to a simpler
> version that gets the expected results.
>
> Fixes: c35a5cfb4150 ("scsi: sg: sg_read(): simplify reading ->pack_id of userland sg_io_hdr_t")
> Fixes: 98aaaec4a150 ("compat_ioctl: reimplement SG_IO handling")
> Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
>  block/scsi_ioctl.c |   29 ------------
>  drivers/scsi/sg.c  |  126 ++++++++++++++++++++++++-----------------------------
>  include/scsi/sg.h  |   30 ++++++++++++
>  3 files changed, 90 insertions(+), 95 deletions(-)
>
> --- a/block/scsi_ioctl.c
> +++ b/block/scsi_ioctl.c
> @@ -20,6 +20,7 @@
>  #include <scsi/scsi.h>
>  #include <scsi/scsi_ioctl.h>
>  #include <scsi/scsi_cmnd.h>
> +#include <scsi/sg.h>
>
>  struct blk_cmd_filter {
>         unsigned long read_ok[BLK_SCSI_CMD_PER_LONG];
> @@ -550,34 +551,6 @@ static inline int blk_send_start_stop(st
>         return __blk_send_generic(q, bd_disk, GPCMD_START_STOP_UNIT, data);
>  }
>
> -#ifdef CONFIG_COMPAT
> -struct compat_sg_io_hdr {
> -       compat_int_t interface_id;      /* [i] 'S' for SCSI generic (required) */
> -       compat_int_t 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 */
> -       compat_uint_t dxfer_len;        /* [i] byte count of data transfer */
> -       compat_uint_t dxferp;           /* [i], [*io] points to data transfer memory
> -                                               or scatter gather list */
> -       compat_uptr_t cmdp;             /* [i], [*i] points to command to perform */
> -       compat_uptr_t sbp;              /* [i], [*o] points to sense_buffer memory */
> -       compat_uint_t timeout;          /* [i] MAX_UINT->no timeout (unit: millisec) */
> -       compat_uint_t flags;            /* [i] 0 -> default, see SG_FLAG... */
> -       compat_int_t pack_id;           /* [i->o] unused internally (normally) */
> -       compat_uptr_t 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 */
> -       compat_int_t resid;             /* [o] dxfer_len - actual_transferred */
> -       compat_uint_t duration;         /* [o] time taken by cmd (unit: millisec) */
> -       compat_uint_t info;             /* [o] auxiliary information */
> -};
> -#endif
> -
>  int put_sg_io_hdr(const struct sg_io_hdr *hdr, void __user *argp)
>  {
>  #ifdef CONFIG_COMPAT
> --- a/drivers/scsi/sg.c
> +++ b/drivers/scsi/sg.c
> @@ -405,6 +405,38 @@ sg_release(struct inode *inode, struct f
>         return 0;
>  }
>
> +static int get_sg_io_pack_id(int *pack_id, void __user *buf, size_t count)
> +{
> +       struct sg_header __user *old_hdr = buf;
> +       int reply_len;
> +
> +       if (count >= SZ_SG_HEADER) {
> +               /* negative reply_len means v3 format, otherwise v1/v2 */
> +               if (get_user(reply_len, &old_hdr->reply_len))
> +                       return -EFAULT;
> +
> +               if (reply_len >= 0)
> +                       return get_user(*pack_id, &old_hdr->pack_id);
> +
> +               if (in_compat_syscall() &&
> +                   count >= sizeof(struct compat_sg_io_hdr)) {
> +                       struct compat_sg_io_hdr __user *hp = buf;
> +
> +                       return get_user(*pack_id, &hp->pack_id);
> +               }
> +
> +               if (count >= sizeof(struct sg_io_hdr)) {
> +                       struct sg_io_hdr __user *hp = buf;
> +
> +                       return get_user(*pack_id, &hp->pack_id);
> +               }
> +       }
> +
> +       /* no valid header was passed, so ignore the pack_id */
> +       *pack_id = -1;
> +       return 0;
> +}
> +
>  static ssize_t
>  sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
>  {
> @@ -413,8 +445,8 @@ sg_read(struct file *filp, char __user *
>         Sg_request *srp;
>         int req_pack_id = -1;
>         sg_io_hdr_t *hp;
> -       struct sg_header *old_hdr = NULL;
> -       int retval = 0;
> +       struct sg_header *old_hdr;
> +       int retval;
>
>         /*
>          * This could cause a response to be stranded. Close the associated
> @@ -429,79 +461,34 @@ sg_read(struct file *filp, char __user *
>         SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
>                                       "sg_read: count=%d\n", (int) count));
>
> -       if (sfp->force_packid && (count >= SZ_SG_HEADER)) {
> -               old_hdr = memdup_user(buf, SZ_SG_HEADER);
> -               if (IS_ERR(old_hdr))
> -                       return PTR_ERR(old_hdr);
> -               if (old_hdr->reply_len < 0) {
> -                       if (count >= SZ_SG_IO_HDR) {
> -                               /*
> -                                * This is stupid.
> -                                *
> -                                * We're copying the whole sg_io_hdr_t from user
> -                                * space just to get the 'pack_id' field. But the
> -                                * field is at different offsets for the compat
> -                                * case, so we'll use "get_sg_io_hdr()" to copy
> -                                * the whole thing and convert it.
> -                                *
> -                                * We could do something like just calculating the
> -                                * offset based of 'in_compat_syscall()', but the
> -                                * 'compat_sg_io_hdr' definition is in the wrong
> -                                * place for that.
> -                                */
> -                               sg_io_hdr_t *new_hdr;
> -                               new_hdr = kmalloc(SZ_SG_IO_HDR, GFP_KERNEL);
> -                               if (!new_hdr) {
> -                                       retval = -ENOMEM;
> -                                       goto free_old_hdr;
> -                               }
> -                               retval = get_sg_io_hdr(new_hdr, buf);
> -                               req_pack_id = new_hdr->pack_id;
> -                               kfree(new_hdr);
> -                               if (retval) {
> -                                       retval = -EFAULT;
> -                                       goto free_old_hdr;
> -                               }
> -                       }
> -               } else
> -                       req_pack_id = old_hdr->pack_id;
> -       }
> +       if (sfp->force_packid)
> +               retval = get_sg_io_pack_id(&req_pack_id, buf, count);
> +       if (retval)
> +               return retval;
> +
>         srp = sg_get_rq_mark(sfp, req_pack_id);
>         if (!srp) {             /* now wait on packet to arrive */
> -               if (atomic_read(&sdp->detaching)) {
> -                       retval = -ENODEV;
> -                       goto free_old_hdr;
> -               }
> -               if (filp->f_flags & O_NONBLOCK) {
> -                       retval = -EAGAIN;
> -                       goto free_old_hdr;
> -               }
> +               if (atomic_read(&sdp->detaching))
> +                       return -ENODEV;
> +               if (filp->f_flags & O_NONBLOCK)
> +                       return -EAGAIN;
>                 retval = wait_event_interruptible(sfp->read_wait,
>                         (atomic_read(&sdp->detaching) ||
>                         (srp = sg_get_rq_mark(sfp, req_pack_id))));
> -               if (atomic_read(&sdp->detaching)) {
> -                       retval = -ENODEV;
> -                       goto free_old_hdr;
> -               }
> -               if (retval) {
> +               if (atomic_read(&sdp->detaching))
> +                       return -ENODEV;
> +               if (retval)
>                         /* -ERESTARTSYS as signal hit process */
> -                       goto free_old_hdr;
> -               }
> -       }
> -       if (srp->header.interface_id != '\0') {
> -               retval = sg_new_read(sfp, buf, count, srp);
> -               goto free_old_hdr;
> +                       return retval;
>         }
> +       if (srp->header.interface_id != '\0')
> +               return sg_new_read(sfp, buf, count, srp);
>
>         hp = &srp->header;
> -       if (old_hdr == NULL) {
> -               old_hdr = kmalloc(SZ_SG_HEADER, GFP_KERNEL);
> -               if (! old_hdr) {
> -                       retval = -ENOMEM;
> -                       goto free_old_hdr;
> -               }
> -       }
> -       memset(old_hdr, 0, SZ_SG_HEADER);
> +       old_hdr = kzalloc(SZ_SG_HEADER, GFP_KERNEL);
> +       if (!old_hdr)
> +               return -ENOMEM;
> +
>         old_hdr->reply_len = (int) hp->timeout;
>         old_hdr->pack_len = old_hdr->reply_len; /* old, strange behaviour */
>         old_hdr->pack_id = hp->pack_id;
> @@ -575,7 +562,12 @@ sg_new_read(Sg_fd * sfp, char __user *bu
>         int err = 0, err2;
>         int len;
>
> -       if (count < SZ_SG_IO_HDR) {
> +       if (in_compat_syscall()) {
> +               if (count < sizeof(struct compat_sg_io_hdr)) {
> +                       err = -EINVAL;
> +                       goto err_out;
> +               }
> +       } else if (count < SZ_SG_IO_HDR) {
>                 err = -EINVAL;
>                 goto err_out;
>         }
> --- a/include/scsi/sg.h
> +++ b/include/scsi/sg.h
> @@ -68,6 +68,36 @@ typedef struct sg_io_hdr
>      unsigned int info;          /* [o] auxiliary information */
>  } sg_io_hdr_t;  /* 64 bytes long (on i386) */
>
> +#if defined(__KERNEL__)
> +#include <linux/compat.h>
> +
> +struct compat_sg_io_hdr {
> +       compat_int_t interface_id;      /* [i] 'S' for SCSI generic (required) */
> +       compat_int_t 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 */
> +       compat_uint_t dxfer_len;        /* [i] byte count of data transfer */
> +       compat_uint_t dxferp;           /* [i], [*io] points to data transfer memory
> +                                               or scatter gather list */
> +       compat_uptr_t cmdp;             /* [i], [*i] points to command to perform */
> +       compat_uptr_t sbp;              /* [i], [*o] points to sense_buffer memory */
> +       compat_uint_t timeout;          /* [i] MAX_UINT->no timeout (unit: millisec) */
> +       compat_uint_t flags;            /* [i] 0 -> default, see SG_FLAG... */
> +       compat_int_t pack_id;           /* [i->o] unused internally (normally) */
> +       compat_uptr_t 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 */
> +       compat_int_t resid;             /* [o] dxfer_len - actual_transferred */
> +       compat_uint_t duration;         /* [o] time taken by cmd (unit: millisec) */
> +       compat_uint_t info;             /* [o] auxiliary information */
> +};
> +#endif
> +
>  #define SG_INTERFACE_ID_ORIG 'S'
>
>  /* Use negative values to flag difference from original sg_header structure */
>
>

-- 
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https://lkft.linaro.org