6.1-stable review patch. If anyone has any objections, please let me know.
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From: Al Viro viro@zeniv.linux.org.uk
[ Upstream commit 053fc4f755ad43cf35210677bcba798ccdc48d0c ]
->permission(), ->get_link() and ->inode_get_acl() might dereference ->s_fs_info (and, in case of ->permission(), ->s_fs_info->fc->user_ns as well) when called from rcu pathwalk.
Freeing ->s_fs_info->fc is rcu-delayed; we need to make freeing ->s_fs_info and dropping ->user_ns rcu-delayed too.
Signed-off-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Sasha Levin sashal@kernel.org --- fs/fuse/cuse.c | 3 +-- fs/fuse/fuse_i.h | 1 + fs/fuse/inode.c | 15 +++++++++++---- 3 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c index c7d882a9fe339..295344a462e1d 100644 --- a/fs/fuse/cuse.c +++ b/fs/fuse/cuse.c @@ -474,8 +474,7 @@ static int cuse_send_init(struct cuse_conn *cc)
static void cuse_fc_release(struct fuse_conn *fc) { - struct cuse_conn *cc = fc_to_cc(fc); - kfree_rcu(cc, fc.rcu); + kfree(fc_to_cc(fc)); }
/** diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 253b9b78d6f13..66c2a99994683 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -872,6 +872,7 @@ struct fuse_mount {
/* Entry on fc->mounts */ struct list_head fc_entry; + struct rcu_head rcu; };
static inline struct fuse_mount *get_fuse_mount_super(struct super_block *sb) diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index f19bdd7cbd779..64618548835b4 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -925,6 +925,14 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm, } EXPORT_SYMBOL_GPL(fuse_conn_init);
+static void delayed_release(struct rcu_head *p) +{ + struct fuse_conn *fc = container_of(p, struct fuse_conn, rcu); + + put_user_ns(fc->user_ns); + fc->release(fc); +} + void fuse_conn_put(struct fuse_conn *fc) { if (refcount_dec_and_test(&fc->count)) { @@ -936,13 +944,12 @@ void fuse_conn_put(struct fuse_conn *fc) if (fiq->ops->release) fiq->ops->release(fiq); put_pid_ns(fc->pid_ns); - put_user_ns(fc->user_ns); bucket = rcu_dereference_protected(fc->curr_bucket, 1); if (bucket) { WARN_ON(atomic_read(&bucket->count) != 1); kfree(bucket); } - fc->release(fc); + call_rcu(&fc->rcu, delayed_release); } } EXPORT_SYMBOL_GPL(fuse_conn_put); @@ -1356,7 +1363,7 @@ EXPORT_SYMBOL_GPL(fuse_send_init); void fuse_free_conn(struct fuse_conn *fc) { WARN_ON(!list_empty(&fc->devices)); - kfree_rcu(fc, rcu); + kfree(fc); } EXPORT_SYMBOL_GPL(fuse_free_conn);
@@ -1895,7 +1902,7 @@ static void fuse_sb_destroy(struct super_block *sb) void fuse_mount_destroy(struct fuse_mount *fm) { fuse_conn_put(fm->fc); - kfree(fm); + kfree_rcu(fm, rcu); } EXPORT_SYMBOL(fuse_mount_destroy);