Re: [PATCH V2] block: fix BLKSECDISCARD zero-length range causing page cache invalidation

friendly ping...

在 2026/7/25 8:23, Zizhi Wo 写道:
> From: Zizhi Wo <[email protected]>
> 
> Commit 697ba0b6ec4a ("block: fix integer overflow in BLKSECDISCARD") fixed
> the start+len overflow via check_add_overflow() but did not handle the
> start=0, len=0 case. There, start + len = 0, so end = 0 passes all checks,
> and truncate_bdev_range()->truncate_inode_pages_range() is then called with
> lend=UINT64_MAX, whitch is the "truncate to the end of file" sentinel, so
> the entire page cache is invalidated.
> 
> Fix this by replacing the validation with blk_validate_byte_range(), which
> already rejects a zero-length range and is what BLKDISCARD uses. This also
> switches the alignment check from a hardcoded 512 to
> bdev_logical_block_size().
> 
> Fixes: 0bd1ed4860d0 ("block: pass inclusive 'lend' parameter to truncate_inode_pages_range")
> Signed-off-by: Zizhi Wo <[email protected]>
> Reviewed-by: Yu Kuai <[email protected]>
> Reviewed-by: Christoph Hellwig <[email protected]>
> Reviewed-by: Bart Van Assche <[email protected]>
> ---
> v2:
> Add the fixtag.
> 
> v1: https://lore.kernel.org/all/[email protected]/
> ---
>   block/ioctl.c | 13 +++++--------
>   1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/block/ioctl.c b/block/ioctl.c
> index 3d4ea1537457..3b7d33a737e8 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -174,12 +174,11 @@ static int blk_ioctl_discard(struct block_device *bdev, blk_mode_t mode,
>   }
>   
>   static int blk_ioctl_secure_erase(struct block_device *bdev, blk_mode_t mode,
>   		void __user *argp)
>   {
> -	uint64_t start, len, end;
> -	uint64_t range[2];
> +	uint64_t range[2], start, len;
>   	int err;
>   
>   	if (!(mode & BLK_OPEN_WRITE))
>   		return -EBADF;
>   	if (!bdev_max_secure_erase_sectors(bdev))
> @@ -187,19 +186,17 @@ static int blk_ioctl_secure_erase(struct block_device *bdev, blk_mode_t mode,
>   	if (copy_from_user(range, argp, sizeof(range)))
>   		return -EFAULT;
>   
>   	start = range[0];
>   	len = range[1];
> -	if ((start & 511) || (len & 511))
> -		return -EINVAL;
> -	if (check_add_overflow(start, len, &end) ||
> -	    end > bdev_nr_bytes(bdev))
> -		return -EINVAL;
> +	err = blk_validate_byte_range(bdev, start, len);
> +	if (err)
> +		return err;
>   
>   	inode_lock(bdev->bd_mapping->host);
>   	filemap_invalidate_lock(bdev->bd_mapping);
> -	err = truncate_bdev_range(bdev, mode, start, end - 1);
> +	err = truncate_bdev_range(bdev, mode, start, start + len - 1);
>   	if (!err)
>   		err = blkdev_issue_secure_erase(bdev, start >> 9, len >> 9,
>   						GFP_KERNEL);
>   	filemap_invalidate_unlock(bdev->bd_mapping);
>   	inode_unlock(bdev->bd_mapping->host);