[PATCH] erofs: include the trailing NUL in FS_IOC_GETFSLABEL

[Gao Xiang]

On 2026/4/1 14:13, Zhan Xusheng wrote:
> erofs_ioctl_get_volume_label() passes strlen(sbi->volume_name) as
> the length to copy_to_user(), which copies the label string without
> the trailing NUL byte.  Since FS_IOC_GETFSLABEL callers expect a
> NUL-terminated string in the FSLABEL_MAX-sized buffer and may not
> pre-zero the buffer, this can cause userspace to read past the label
> into uninitialised stack memory.
> 
> Fix this by using strlen() + 1 to include the NUL terminator,
> consistent with how ext4 and xfs implement FS_IOC_GETFSLABEL.
> 
> Signed-off-by: Zhan Xusheng <zhanxusheng at xiaomi.com>

Thanks,

Fixes: 1cf12c717741 ("erofs: Add support for FS_IOC_GETFSLABEL")
Reviewed-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Thanks,
Gao Xiang