fuse: fix bad inode

Jan Kara's analysis of the syzbot report (edited):

  The reproducer opens a directory on FUSE filesystem, it then attaches
  dnotify mark to the open directory.  After that a fuse_do_getattr() call
  finds that attributes returned by the server are inconsistent, and calls
  make_bad_inode() which, among other things does:

          inode->i_mode = S_IFREG;

  This then confuses dnotify which doesn't tear down its structures
  properly and eventually crashes.

Avoid calling make_bad_inode() on a live inode: switch to a private flag on
the fuse inode.  Also add the test to ops which the bad_inode_ops would
have caught.

This bug goes back to the initial merge of fuse in 2.6.14...

Reported-by: syzbot+f427adf9324b92652ccc@syzkaller.appspotmail.com
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Jan Kara <jack@suse.cz>
Cc: <stable@vger.kernel.org>

diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index 5a48cee..f529075 100644 (file)
--- a/fs/fuse/acl.c
+++ b/fs/fuse/acl.c
@@ -19,6 +19,9 @@ struct posix_acl *fuse_get_acl(struct inode *inode, int type)
        void *value = NULL;
        struct posix_acl *acl;
 
+       if (fuse_is_bad(inode))
+               return ERR_PTR(-EIO);
+
        if (!fc->posix_acl || fc->no_getxattr)
                return NULL;
 
@@ -53,6 +56,9 @@ int fuse_set_acl(struct inode *inode, struct posix_acl *acl, int type)
        const char *name;
        int ret;
 
+       if (fuse_is_bad(inode))
+               return -EIO;
+
        if (!fc->posix_acl || fc->no_setxattr)
                return -EOPNOTSUPP;
 

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 5d43af1..78f9f20 100644 (file)
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -202,7 +202,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
        int ret;
 
        inode = d_inode_rcu(entry);
-       if (inode && is_bad_inode(inode))
+       if (inode && fuse_is_bad(inode))
                goto invalid;
        else if (time_before64(fuse_dentry_time(entry), get_jiffies_64()) ||
                 (flags & (LOOKUP_EXCL | LOOKUP_REVAL))) {
@@ -462,6 +462,9 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
        bool outarg_valid = true;
        bool locked;
 
+       if (fuse_is_bad(dir))
+               return ERR_PTR(-EIO);
+
        locked = fuse_lock_inode(dir);
        err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name,
                               &outarg, &inode);
@@ -611,6 +614,9 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
        struct fuse_conn *fc = get_fuse_conn(dir);
        struct dentry *res = NULL;
 
+       if (fuse_is_bad(dir))
+               return -EIO;
+
        if (d_in_lookup(entry)) {
                res = fuse_lookup(dir, entry, 0);
                if (IS_ERR(res))
@@ -659,6 +665,9 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args,
        int err;
        struct fuse_forget_link *forget;
 
+       if (fuse_is_bad(dir))
+               return -EIO;
+
        forget = fuse_alloc_forget();
        if (!forget)
                return -ENOMEM;
@@ -786,6 +795,9 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
        struct fuse_mount *fm = get_fuse_mount(dir);
        FUSE_ARGS(args);
 
+       if (fuse_is_bad(dir))
+               return -EIO;
+
        args.opcode = FUSE_UNLINK;
        args.nodeid = get_node_id(dir);
        args.in_numargs = 1;
@@ -822,6 +834,9 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
        struct fuse_mount *fm = get_fuse_mount(dir);
        FUSE_ARGS(args);
 
+       if (fuse_is_bad(dir))
+               return -EIO;
+
        args.opcode = FUSE_RMDIR;
        args.nodeid = get_node_id(dir);
        args.in_numargs = 1;
@@ -900,6 +915,9 @@ static int fuse_rename2(struct inode *olddir, struct dentry *oldent,
        struct fuse_conn *fc = get_fuse_conn(olddir);
        int err;
 
+       if (fuse_is_bad(olddir))
+               return -EIO;
+
        if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
                return -EINVAL;
 
@@ -1035,7 +1053,7 @@ static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
        if (!err) {
                if (fuse_invalid_attr(&outarg.attr) ||
                    (inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
-                       make_bad_inode(inode);
+                       fuse_make_bad(inode);
                        err = -EIO;
                } else {
                        fuse_change_attributes(inode, &outarg.attr,
@@ -1237,6 +1255,9 @@ static int fuse_permission(struct inode *inode, int mask)
        bool refreshed = false;
        int err = 0;
 
+       if (fuse_is_bad(inode))
+               return -EIO;
+
        if (!fuse_allow_current_process(fc))
                return -EACCES;
 
@@ -1332,7 +1353,7 @@ static const char *fuse_get_link(struct dentry *dentry, struct inode *inode,
        int err;
 
        err = -EIO;
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                goto out_err;
 
        if (fc->cache_symlinks)
@@ -1380,7 +1401,7 @@ static int fuse_dir_fsync(struct file *file, loff_t start, loff_t end,
        struct fuse_conn *fc = get_fuse_conn(inode);
        int err;
 
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                return -EIO;
 
        if (fc->no_fsyncdir)
@@ -1679,7 +1700,7 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 
        if (fuse_invalid_attr(&outarg.attr) ||
            (inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
-               make_bad_inode(inode);
+               fuse_make_bad(inode);
                err = -EIO;
                goto error;
        }
@@ -1742,6 +1763,9 @@ static int fuse_setattr(struct dentry *entry, struct iattr *attr)
        struct file *file = (attr->ia_valid & ATTR_FILE) ? attr->ia_file : NULL;
        int ret;
 
+       if (fuse_is_bad(inode))
+               return -EIO;
+
        if (!fuse_allow_current_process(get_fuse_conn(inode)))
                return -EACCES;
 
@@ -1800,6 +1824,9 @@ static int fuse_getattr(const struct path *path, struct kstat *stat,
        struct inode *inode = d_inode(path->dentry);
        struct fuse_conn *fc = get_fuse_conn(inode);
 
+       if (fuse_is_bad(inode))
+               return -EIO;
+
        if (!fuse_allow_current_process(fc)) {
                if (!request_mask) {
                        /*

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 3498853..8cccecb 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -232,6 +232,9 @@ int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
        bool dax_truncate = (file->f_flags & O_TRUNC) &&
                          fc->atomic_o_trunc && FUSE_IS_DAX(inode);
 
+       if (fuse_is_bad(inode))
+               return -EIO;
+
        err = generic_file_open(inode, file);
        if (err)
                return err;
@@ -469,7 +472,7 @@ static int fuse_flush(struct file *file, fl_owner_t id)
        FUSE_ARGS(args);
        int err;
 
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                return -EIO;
 
        err = write_inode_now(inode, 1);
@@ -541,7 +544,7 @@ static int fuse_fsync(struct file *file, loff_t start, loff_t end,
        struct fuse_conn *fc = get_fuse_conn(inode);
        int err;
 
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                return -EIO;
 
        inode_lock(inode);
@@ -865,7 +868,7 @@ static int fuse_readpage(struct file *file, struct page *page)
        int err;
 
        err = -EIO;
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                goto out;
 
        err = fuse_do_readpage(file, page);
@@ -958,7 +961,7 @@ static void fuse_readahead(struct readahead_control *rac)
        struct fuse_conn *fc = get_fuse_conn(inode);
        unsigned int i, max_pages, nr_pages = 0;
 
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                return;
 
        max_pages = min_t(unsigned int, fc->max_pages,
@@ -1570,7 +1573,7 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
        struct fuse_file *ff = file->private_data;
        struct inode *inode = file_inode(file);
 
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                return -EIO;
 
        if (FUSE_IS_DAX(inode))
@@ -1588,7 +1591,7 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
        struct fuse_file *ff = file->private_data;
        struct inode *inode = file_inode(file);
 
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                return -EIO;
 
        if (FUSE_IS_DAX(inode))
@@ -2187,7 +2190,7 @@ static int fuse_writepages(struct address_space *mapping,
        int err;
 
        err = -EIO;
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                goto out;
 
        data.inode = inode;
@@ -2972,7 +2975,7 @@ long fuse_ioctl_common(struct file *file, unsigned int cmd,
        if (!fuse_allow_current_process(fc))
                return -EACCES;
 
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                return -EIO;
 
        return fuse_do_ioctl(file, cmd, arg, flags);

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index d414c78..7c4b8cb 100644 (file)
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -172,6 +172,8 @@ enum {
        FUSE_I_INIT_RDPLUS,
        /** An operation changing file size is in progress  */
        FUSE_I_SIZE_UNSTABLE,
+       /* Bad inode */
+       FUSE_I_BAD,
 };
 
 struct fuse_conn;
@@ -859,6 +861,16 @@ static inline u64 fuse_get_attr_version(struct fuse_conn *fc)
        return atomic64_read(&fc->attr_version);
 }
 
+static inline void fuse_make_bad(struct inode *inode)
+{
+       set_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state);
+}
+
+static inline bool fuse_is_bad(struct inode *inode)
+{
+       return unlikely(test_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state));
+}
+
 /** Device operations */
 extern const struct file_operations fuse_dev_operations;
 

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 36ab053..b0e18b4 100644 (file)
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -132,7 +132,7 @@ static void fuse_evict_inode(struct inode *inode)
                        fi->forget = NULL;
                }
        }
-       if (S_ISREG(inode->i_mode) && !is_bad_inode(inode)) {
+       if (S_ISREG(inode->i_mode) && !fuse_is_bad(inode)) {
                WARN_ON(!list_empty(&fi->write_files));
                WARN_ON(!list_empty(&fi->queued_writes));
        }
@@ -352,7 +352,7 @@ retry:
                unlock_new_inode(inode);
        } else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
                /* Inode has changed type, any I/O on the old should fail */
-               make_bad_inode(inode);
+               fuse_make_bad(inode);
                iput(inode);
                goto retry;
        }

diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
index 3b5e910..3441ffa 100644 (file)
--- a/fs/fuse/readdir.c
+++ b/fs/fuse/readdir.c
@@ -207,7 +207,7 @@ retry:
                        dput(dentry);
                        goto retry;
                }
-               if (is_bad_inode(inode)) {
+               if (fuse_is_bad(inode)) {
                        dput(dentry);
                        return -EIO;
                }
@@ -568,7 +568,7 @@ int fuse_readdir(struct file *file, struct dir_context *ctx)
        struct inode *inode = file_inode(file);
        int err;
 
-       if (is_bad_inode(inode))
+       if (fuse_is_bad(inode))
                return -EIO;
 
        mutex_lock(&ff->readdir.lock);

diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c
index 371bdcb..cdea18d 100644 (file)
--- a/fs/fuse/xattr.c
+++ b/fs/fuse/xattr.c
@@ -113,6 +113,9 @@ ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size)
        struct fuse_getxattr_out outarg;
        ssize_t ret;
 
+       if (fuse_is_bad(inode))
+               return -EIO;
+
        if (!fuse_allow_current_process(fm->fc))
                return -EACCES;
 
@@ -178,6 +181,9 @@ static int fuse_xattr_get(const struct xattr_handler *handler,
                         struct dentry *dentry, struct inode *inode,
                         const char *name, void *value, size_t size)
 {
+       if (fuse_is_bad(inode))
+               return -EIO;
+
        return fuse_getxattr(inode, name, value, size);
 }
 
@@ -186,6 +192,9 @@ static int fuse_xattr_set(const struct xattr_handler *handler,
                          const char *name, const void *value, size_t size,
                          int flags)
 {
+       if (fuse_is_bad(inode))
+               return -EIO;
+
        if (!value)
                return fuse_removexattr(inode, name);