When "ovl_is_inuse" true case, trap inode reference not put. plus adding the comment explaining sequence of ovl_is_inuse after ovl_setup_trap.

Fixes: 0be0bfd2de9d ("ovl: fix regression caused by overlapping layers..") Cc: stable@vger.kernel.org # v4.19+ Reviewed-by: Amir Goldstein amir73il@gmail.com Signed-off-by: youngjun her0gyugyu@gmail.com --- fs/overlayfs/super.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 91476bc422f9..3097142b1e23 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1493,14 +1493,22 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, if (err < 0) goto out;

+ /* + * Check if lower root conflicts with this overlay layers before checking + * if it is in-use as upperdir/workdir of "another" mount, because we do + * not bother to check in ovl_is_inuse() if the upperdir/workdir is in fact + * in-use by our upperdir/workdir. + */ err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir"); if (err) goto out;

if (ovl_is_inuse(stack[i].dentry)) { err = ovl_report_in_use(ofs, "lowerdir"); - if (err) + if (err) { + iput(trap); goto out; + } }

mnt = clone_private_mount(&stack[i]);