4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Amir Goldstein <amir73il@xxxxxxxxx>
commit 67810693077afc1ebf9e1646af300436cb8103c2 upstream.
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')
Cc: <stable@xxxxxxxxxxxxxxx> # v4.14
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/overlayfs/readdir.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -623,6 +623,21 @@ static int ovl_fill_real(struct dir_cont
return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
}
+static bool ovl_is_impure_dir(struct file *file)
+{
+ struct ovl_dir_file *od = file->private_data;
+ struct inode *dir = d_inode(file->f_path.dentry);
+
+ /*
+ * 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.
+ */
+ return od->is_upper && ovl_test_flag(OVL_IMPURE, dir);
+
+}
+
static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
{
int err;
@@ -646,7 +661,7 @@ static int ovl_iterate_real(struct file
rdt.parent_ino = stat.ino;
}
- if (ovl_test_flag(OVL_IMPURE, d_inode(dir))) {
+ if (ovl_is_impure_dir(file)) {
rdt.cache = ovl_cache_get_impure(&file->f_path);
if (IS_ERR(rdt.cache))
return PTR_ERR(rdt.cache);
@@ -676,7 +691,7 @@ static int ovl_iterate(struct file *file
* entries.
*/
if (ovl_same_sb(dentry->d_sb) &&
- (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
+ (ovl_is_impure_dir(file) ||
OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent)))) {
return ovl_iterate_real(file, ctx);
}
