From b753b0be45ae3eb4a37a6a9efb69a3ba486b81ea Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Thu, 10 Nov 2022 12:16:34 -0800 Subject: [PATCH] ext4: don't fail GETFSUUID when the caller provides a long buffer commit a7e9d977e031fceefe1e7cd69ebd7202d5758b56 upstream. 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 Reviewed-by: Catherine Hoang Link: https://lore.kernel.org/r/166811139478.327006.13879198441587445544.stgit@magnolia Signed-off-by: Theodore Ts'o Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman --- 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 e5f6005..5a12f87 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 -EINVAL; } - 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; } -- 2.7.4