The commit is pushed to "branch-rh8-4.18.0-305.3.1.vz8.7.x-ovz" and will appear
at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-305.3.1.vz8.7.11
------>
commit 8250ff41d1900f88dfba91bc138e2485c95faa11
Author: Konstantin Khorenko <[email protected]>
Date: Fri Sep 10 19:35:27 2021 +0300
ve/fs/binfmt: clean bm_data reference from ve on err path
1. Make sure ve->binfmt_misc is NULL if error happens on binfmt_misc
mount, otherwise on next attempt to mount binfmt_misc (probably
successful) we won't even try to allocate/init structures for it.
2. The current bm_fill_super() code makes us suppose we can get into
the function with ve->binfmt_misc already initialized. If this is true
and simple_fill_super() fails we will free preconfigured ve->binfmt_misc
without proper deinitialization (ve_binfmt_fini()).
Hopefully this is a wrong assumption, so rewrite the code not to confuse
readers.
Fixes: 90fb0e274 ("ve/fs/binfmt: virtualization")
https://jira.sw.ru/browse/PSBM-131994
Signed-off-by: Alexander Mikhalitsyn <[email protected]>
Signed-off-by: Konstantin Khorenko <[email protected]>
---
fs/binfmt_misc.c | 29 ++++++++++++++++++++---------
1 file changed, 20 insertions(+), 9 deletions(-)
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 2b586d61f4a9..0946e7e6caa5 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -853,18 +853,28 @@ static int bm_fill_super(struct super_block *sb, struct
fs_context *fc)
};
struct ve_struct *ve = get_exec_env();
- struct binfmt_misc *bm_data = ve->binfmt_misc;
+ struct binfmt_misc *bm_data;
- if (!bm_data) {
- bm_data = kzalloc(sizeof(struct binfmt_misc), GFP_KERNEL);
- if (!bm_data)
- return -ENOMEM;
+ /*
+ * bm_get_tree()
+ * get_tree_keyed(fc, bm_fill_super, get_ve(ve))
+ * fc->s_fs_info = current VE
+ * vfs_get_super(fc, vfs_get_keyed_super, bm_fill_super)
+ * sb = sget_fc(fc, test, set_anon_super_fc)
+ * if (!sb->s_root) {
+ * err = bm_fill_super(sb, fc);
+ *
+ * => we should never get here with initialized ve->binfmt_misc.
+ */
+ if (WARN_ON_ONCE(ve->binfmt_misc))
+ return -EEXIST;
- INIT_LIST_HEAD(&bm_data->entries);
- rwlock_init(&bm_data->entries_lock);
+ bm_data = kzalloc(sizeof(struct binfmt_misc), GFP_KERNEL);
+ if (!bm_data)
+ return -ENOMEM;
- ve->binfmt_misc = bm_data;
- }
+ INIT_LIST_HEAD(&bm_data->entries);
+ rwlock_init(&bm_data->entries_lock);
err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
if (err) {
@@ -874,6 +884,7 @@ static int bm_fill_super(struct super_block *sb, struct
fs_context *fc)
sb->s_op = &s_ops;
+ ve->binfmt_misc = bm_data;
bm_data->enabled = 1;
return 0;
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