4.9-stable review patch. If anyone has any objections, please let me know.
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From: Miklos Szeredi mszeredi@redhat.com
commit 63576c13bd17848376c8ba4a98f5d5151140c4ac upstream.
If parallel dirops are enabled in FUSE_INIT reply, then first operation may leave fi->mutex held.
Reported-by: syzbot syzbot+3f7b29af1baa9d0a55be@syzkaller.appspotmail.com Fixes: 5c672ab3f0ee ("fuse: serialize dirops by default") Cc: stable@vger.kernel.org # v4.7 Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/fuse/dir.c | 10 ++++++---- fs/fuse/fuse_i.h | 4 ++-- fs/fuse/inode.c | 14 ++++++++++---- 3 files changed, 18 insertions(+), 10 deletions(-)
--- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -355,11 +355,12 @@ static struct dentry *fuse_lookup(struct struct inode *inode; struct dentry *newent; bool outarg_valid = true; + bool locked;
- fuse_lock_inode(dir); + locked = fuse_lock_inode(dir); err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name, &outarg, &inode); - fuse_unlock_inode(dir); + fuse_unlock_inode(dir, locked); if (err == -ENOENT) { outarg_valid = false; err = 0; @@ -1336,6 +1337,7 @@ static int fuse_readdir(struct file *fil struct fuse_conn *fc = get_fuse_conn(inode); struct fuse_req *req; u64 attr_version = 0; + bool locked;
if (is_bad_inode(inode)) return -EIO; @@ -1363,9 +1365,9 @@ static int fuse_readdir(struct file *fil fuse_read_fill(req, file, ctx->pos, PAGE_SIZE, FUSE_READDIR); } - fuse_lock_inode(inode); + locked = fuse_lock_inode(inode); fuse_request_send(fc, req); - fuse_unlock_inode(inode); + fuse_unlock_inode(inode, locked); nbytes = req->out.args[0].size; err = req->out.h.error; fuse_put_request(fc, req); --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -967,8 +967,8 @@ int fuse_do_setattr(struct dentry *dentr
void fuse_set_initialized(struct fuse_conn *fc);
-void fuse_unlock_inode(struct inode *inode); -void fuse_lock_inode(struct inode *inode); +void fuse_unlock_inode(struct inode *inode, bool locked); +bool fuse_lock_inode(struct inode *inode);
int fuse_setxattr(struct inode *inode, const char *name, const void *value, size_t size, int flags); --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -356,15 +356,21 @@ int fuse_reverse_inval_inode(struct supe return 0; }
-void fuse_lock_inode(struct inode *inode) +bool fuse_lock_inode(struct inode *inode) { - if (!get_fuse_conn(inode)->parallel_dirops) + bool locked = false; + + if (!get_fuse_conn(inode)->parallel_dirops) { mutex_lock(&get_fuse_inode(inode)->mutex); + locked = true; + } + + return locked; }
-void fuse_unlock_inode(struct inode *inode) +void fuse_unlock_inode(struct inode *inode, bool locked) { - if (!get_fuse_conn(inode)->parallel_dirops) + if (locked) mutex_unlock(&get_fuse_inode(inode)->mutex); }