The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Possible dependencies:

b76abb515746 ("ext4: dont return EINVAL from GETFSUUID when reporting UUID length") d95efb14c0b8 ("ext4: add ioctls to get/set the ext4 superblock uuid") bbc605cdb1e1 ("ext4: implement support for get/set fs label") 351a0a3fbc35 ("ext4: add ioctl EXT4_IOC_CHECKPOINT") 4db5c2e6236f ("ext4: convert to fileattr") 7d6beb71da3c ("Merge tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b76abb5157468756163fe7e3431c9fe32cba57ca Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" djwong@kernel.org Date: Thu, 10 Nov 2022 12:16:29 -0800 Subject: [PATCH] ext4: dont return EINVAL from GETFSUUID when reporting UUID length

If userspace calls this ioctl with fsu_length (the length of the fsuuid.fsu_uuid array) set to zero, ext4 copies the desired uuid length out to userspace. The kernel call returned a result from a valid input, so the return value here should be zero, not EINVAL.

While we're at it, fix the copy_to_user call to make it clear that we're only copying out fsu_len.

Signed-off-by: Darrick J. Wong djwong@kernel.org Reviewed-by: Catherine Hoang catherine.hoang@oracle.com Link: https://lore.kernel.org/r/166811138914.327006.9241306894437166566.stgit@magn... Signed-off-by: Theodore Ts'o tytso@mit.edu Cc: stable@kernel.org

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index e5f60057db5b..beedaebab21c 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -1154,9 +1154,10 @@ static int ext4_ioctl_getuuid(struct ext4_sb_info *sbi,

if (fsuuid.fsu_len == 0) { fsuuid.fsu_len = UUID_SIZE; - if (copy_to_user(ufsuuid, &fsuuid, sizeof(fsuuid.fsu_len))) + if (copy_to_user(&ufsuuid->fsu_len, &fsuuid.fsu_len, + sizeof(fsuuid.fsu_len))) return -EFAULT; - return -EINVAL; + return 0; }

if (fsuuid.fsu_len != UUID_SIZE || fsuuid.fsu_flags != 0)