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loop: don't change loop device under exclusive opener in loop_set_status #369

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loop: don't change loop device under exclusive opener in loop_set_status #369

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41 changes: 30 additions & 11 deletions drivers/block/loop.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1226,13 +1226,24 @@ static int loop_clr_fd(struct loop_device *lo)
}

static int
loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
loop_set_status(struct loop_device *lo, blk_mode_t mode,
struct block_device *bdev, const struct loop_info64 *info)
{
int err;
bool partscan = false;
bool size_changed = false;
unsigned int memflags;

/*
* If we don't hold exclusive handle for the device, upgrade to it
* here to avoid changing device under exclusive owner.
*/
if (!(mode & BLK_OPEN_EXCL)) {
err = bd_prepare_to_claim(bdev, loop_set_status, NULL);
if (err)
goto out_reread_partitions;
}

err = mutex_lock_killable(&lo->lo_mutex);
if (err)
return err;
Expand Down Expand Up @@ -1274,6 +1285,9 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
}
out_unlock:
mutex_unlock(&lo->lo_mutex);
if (!(mode & BLK_OPEN_EXCL))
bd_abort_claiming(bdev, loop_set_status);
out_reread_partitions:
if (partscan)
loop_reread_partitions(lo);

Expand Down Expand Up @@ -1353,25 +1367,29 @@ loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
}

static int
loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
loop_set_status_old(struct loop_device *lo, blk_mode_t mode,
struct block_device *bdev,
const struct loop_info __user *arg)
{
struct loop_info info;
struct loop_info64 info64;

if (copy_from_user(&info, arg, sizeof (struct loop_info)))
return -EFAULT;
loop_info64_from_old(&info, &info64);
return loop_set_status(lo, &info64);
return loop_set_status(lo, mode, bdev, &info64);
}

static int
loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
loop_set_status64(struct loop_device *lo, blk_mode_t mode,
struct block_device *bdev,
const struct loop_info64 __user *arg)
{
struct loop_info64 info64;

if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
return -EFAULT;
return loop_set_status(lo, &info64);
return loop_set_status(lo, mode, bdev, &info64);
}

static int
Expand Down Expand Up @@ -1550,14 +1568,14 @@ static int lo_ioctl(struct block_device *bdev, blk_mode_t mode,
case LOOP_SET_STATUS:
err = -EPERM;
if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
err = loop_set_status_old(lo, argp);
err = loop_set_status_old(lo, mode, bdev, argp);
break;
case LOOP_GET_STATUS:
return loop_get_status_old(lo, argp);
case LOOP_SET_STATUS64:
err = -EPERM;
if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
err = loop_set_status64(lo, argp);
err = loop_set_status64(lo, mode, bdev, argp);
break;
case LOOP_GET_STATUS64:
return loop_get_status64(lo, argp);
Expand Down Expand Up @@ -1651,16 +1669,17 @@ loop_info64_to_compat(const struct loop_info64 *info64,
}

static int
loop_set_status_compat(struct loop_device *lo,
const struct compat_loop_info __user *arg)
loop_set_status_compat(struct loop_device *lo, blk_mode_t mode,
struct block_device *bdev,
const struct compat_loop_info __user *arg)
{
struct loop_info64 info64;
int ret;

ret = loop_info64_from_compat(arg, &info64);
if (ret < 0)
return ret;
return loop_set_status(lo, &info64);
return loop_set_status(lo, mode, bdev, &info64);
}

static int
Expand All @@ -1686,7 +1705,7 @@ static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode,

switch(cmd) {
case LOOP_SET_STATUS:
err = loop_set_status_compat(lo,
err = loop_set_status_compat(lo, mode, bdev,
(const struct compat_loop_info __user *)arg);
break;
case LOOP_GET_STATUS:
Expand Down
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