Only upper dir can be impure, but if we are in the middle of
iterating a lower real dir, dir could be copied up and marked
impure. We only want the impure cache if we started iterating
a real upper dir to begin with.
Aditya Kali reported that the following reproducer hits the
WARN_ON(!cache->refcount) in ovl_get_cache():
docker run --rm drupal:8.5.4-fpm-alpine \
sh -c 'cd /var/www/html/vendor/symfony && \
chown -R www-data:www-data . && ls -l .'
Reported-by: Aditya Kali <adityakali@xxxxxxxxxx>
Tested-by: Aditya Kali <adityakali@xxxxxxxxxx>
Fixes: 4edb83bb1041 ('ovl: constant d_ino for non-merge dirs')
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/readdir.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index ef1fe42ff7bb..bccbb3ee9932 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -696,7 +696,13 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
rdt.parent_ino = stat.ino;
}
- if (ovl_test_flag(OVL_IMPURE, d_inode(dir))) {
+ /*
+ * Only upper dir can be impure, but if we are in the middle of
+ * iterating a lower real dir, dir could be copied up and marked
+ * impure. We only want the impure cache if we started iterating
+ * a real upper dir to begin with.
+ */
+ if (od->is_upper && ovl_test_flag(OVL_IMPURE, d_inode(dir))) {
rdt.cache = ovl_cache_get_impure(&file->f_path);
if (IS_ERR(rdt.cache))
return PTR_ERR(rdt.cache);
@@ -721,14 +727,16 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
if (od->is_real) {
/*
- * If parent is merge, then need to adjust d_ino for '..', if
- * dir is impure then need to adjust d_ino for copied up
- * entries.
+ * If xino is enabled, need to adjust lower d_ino.
+ * If parent is merge, then need to adjust d_ino for '..'.
+ * If dir is upper and impure then need to adjust d_ino for
+ * copied up entries.
*/
if (ovl_xino_bits(dentry->d_sb) ||
(ovl_same_sb(dentry->d_sb) &&
- (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
- OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
+ (OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent)) ||
+ (od->is_upper &&
+ ovl_test_flag(OVL_IMPURE, d_inode(dentry)))))) {
return ovl_iterate_real(file, ctx);
}
return iterate_dir(od->realfile, ctx);
--
2.7.4
--
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