> On Nov 10, 2022, at 12:16 PM, Darrick J. Wong <djwong@xxxxxxxxxx> wrote: > > From: Darrick J. Wong <djwong@xxxxxxxxxx> > > If userspace provides a longer UUID buffer than is required, we > shouldn't fail the call with EINVAL -- rather, we can fill the caller's > buffer with the bytes we /can/ fill, and update the length field to > reflect what we copied. This doesn't break the UAPI since we're > enabling a case that currently fails, and so far Ted hasn't released a > version of e2fsprogs that uses the new ext4 ioctl. > > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> Looks good Reviewed-by: Catherine Hoang <catherine.hoang@xxxxxxxxxx> > --- > fs/ext4/ioctl.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > > diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c > index 5f91f3ad3e50..31e643795016 100644 > --- a/fs/ext4/ioctl.c > +++ b/fs/ext4/ioctl.c > @@ -1159,14 +1159,16 @@ static int ext4_ioctl_getuuid(struct ext4_sb_info *sbi, > return 0; > } > > - if (fsuuid.fsu_len != UUID_SIZE || fsuuid.fsu_flags != 0) > + if (fsuuid.fsu_len < UUID_SIZE || fsuuid.fsu_flags != 0) > return -EINVAL; > > lock_buffer(sbi->s_sbh); > memcpy(uuid, sbi->s_es->s_uuid, UUID_SIZE); > unlock_buffer(sbi->s_sbh); > > - if (copy_to_user(&ufsuuid->fsu_uuid[0], uuid, UUID_SIZE)) > + fsuuid.fsu_len = UUID_SIZE; > + if (copy_to_user(ufsuuid, &fsuuid, sizeof(fsuuid)) || > + copy_to_user(&ufsuuid->fsu_uuid[0], uuid, UUID_SIZE)) > return -EFAULT; > return 0; > } >
