Re: [PATCH 3/4] block: add IOC_PR_READ_KEYS ioctl

[kernel test robot <lkp@intel.com>]

Hi Stefan,

kernel test robot noticed the following build warnings:

[auto build test WARNING on mkp-scsi/for-next]
[also build test WARNING on axboe/for-next jejb-scsi/for-next linus/master v6.18-rc7 next-20251126]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Stefan-Hajnoczi/scsi-sd-reject-invalid-pr_read_keys-num_keys-values/20251127-003756
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git for-next
patch link:    https://lore.kernel.org/r/20251126163600.583036-4-stefanha%40redhat.com
patch subject: [PATCH 3/4] block: add IOC_PR_READ_KEYS ioctl
config: loongarch-allnoconfig (https://download.01.org/0day-ci/archive/20251127/202511270125.CJ6M2RHv-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9e9fe08b16ea2c4d9867fb4974edf2a3776d6ece)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251127/202511270125.CJ6M2RHv-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511270125.CJ6M2RHv-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> block/ioctl.c:443:21: warning: result of comparison of constant 2305843009213693951 with expression of type '__u32' (aka 'unsigned int') is always false [-Wtautological-constant-out-of-range-compare]
     443 |         if (inout.num_keys > -sizeof(*keys_info) / sizeof(keys_info->keys[0]))
         |             ~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   1 warning generated.


vim +443 block/ioctl.c

   426	
   427	static int blkdev_pr_read_keys(struct block_device *bdev, blk_mode_t mode,
   428			struct pr_read_keys __user *arg)
   429	{
   430		const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
   431		struct pr_keys *keys_info __free(kfree) = NULL;
   432		struct pr_read_keys inout;
   433		int ret;
   434	
   435		if (!blkdev_pr_allowed(bdev, mode))
   436			return -EPERM;
   437		if (!ops || !ops->pr_read_keys)
   438			return -EOPNOTSUPP;
   439	
   440		if (copy_from_user(&inout, arg, sizeof(inout)))
   441			return -EFAULT;
   442	
 > 443		if (inout.num_keys > -sizeof(*keys_info) / sizeof(keys_info->keys[0]))
   444			return -EINVAL;
   445	
   446		size_t keys_info_len = struct_size(keys_info, keys, inout.num_keys);
   447	
   448		keys_info = kzalloc(keys_info_len, GFP_KERNEL);
   449		if (!keys_info)
   450			return -ENOMEM;
   451	
   452		keys_info->num_keys = inout.num_keys;
   453	
   454		ret = ops->pr_read_keys(bdev, keys_info);
   455		if (ret)
   456			return ret;
   457	
   458		/* Copy out individual keys */
   459		u64 __user *keys_ptr = u64_to_user_ptr(inout.keys_ptr);
   460		u32 num_copy_keys = min(inout.num_keys, keys_info->num_keys);
   461		size_t keys_copy_len = num_copy_keys * sizeof(keys_info->keys[0]);
   462	
   463		if (copy_to_user(keys_ptr, keys_info->keys, keys_copy_len))
   464			return -EFAULT;
   465	
   466		/* Copy out the arg struct */
   467		inout.generation = keys_info->generation;
   468		inout.num_keys = keys_info->num_keys;
   469	
   470		if (copy_to_user(arg, &inout, sizeof(inout)))
   471			return -EFAULT;
   472		return ret;
   473	}
   474	

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