The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5d069dbe8aaf2a197142558b6fb2978189ba3454 Mon Sep 17 00:00:00 2001

From: Miklos Szeredi mszeredi@redhat.com Date: Thu, 10 Dec 2020 15:33:14 +0100 Subject: [PATCH] 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 5a48cee6d7d3..f529075a2ce8 100644 --- 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 5d43af1169b7..78f9f209078c 100644 --- 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 349885353036..8cccecb55fb8 100644 --- 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 d414c787e362..7c4b8cb93f9f 100644 --- 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 36ab05315828..b0e18b470e91 100644 --- 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 @@ struct inode *fuse_iget(struct super_block *sb, u64 nodeid, 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 3b5e91045871..3441ffa740f3 100644 --- a/fs/fuse/readdir.c +++ b/fs/fuse/readdir.c @@ -207,7 +207,7 @@ static int fuse_direntplus_link(struct file *file, 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 371bdcbc7233..cdea18de94f7 100644 --- 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);