[PATCH 5.4 08/13] fuse: fix bad inode

Greg Kroah-Hartman
2021-01-07T14:36:01Z

From: Miklos Szeredi <mszeredi@redhat.com>

[ Upstream commit 5d069dbe8aaf2a197142558b6fb2978189ba3454 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/fuse/acl.c | 6 ++++++
fs/fuse/dir.c | 37 ++++++++++++++++++++++++++++++++-----
fs/fuse/file.c | 19 +++++++++++--------
fs/fuse/fuse_i.h | 12 ++++++++++++
fs/fuse/inode.c | 4 ++--
fs/fuse/readdir.c | 4 ++--
fs/fuse/xattr.c | 9 +++++++++
7 files changed, 74 insertions(+), 17 deletions(-)

diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index 5a48cee6d7d33..f529075a2ce87 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 ee190119f45cc..60378f3baaae1 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -201,7 +201,7 @@ 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_REVAL)) {
@@ -386,6 +386,9 @@ 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);
@@ -529,6 +532,9 @@ 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))
@@ -577,6 +583,9 @@ static int create_new_entry(struct fuse_conn *fc, 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;
@@ -704,6 +713,9 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
struct fuse_conn *fc = get_fuse_conn(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;
@@ -740,6 +752,9 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
struct fuse_conn *fc = get_fuse_conn(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;
@@ -818,6 +833,9 @@ 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))
return -EINVAL;

@@ -953,7 +971,7 @@ 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,
@@ -1155,6 +1173,9 @@ 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;

@@ -1250,7 +1271,7 @@ 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)
@@ -1298,7 +1319,7 @@ 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)
@@ -1575,7 +1596,7 @@ 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;
}
@@ -1631,6 +1652,9 @@ 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;

@@ -1689,6 +1713,9 @@ 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))
return -EACCES;

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ab4fc1255aca8..1e1aef1bc20b3 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -222,6 +222,9 @@ int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
fc->atomic_o_trunc &&
fc->writeback_cache;

+ if (fuse_is_bad(inode))
+ return -EIO;
+
err = generic_file_open(inode, file);
if (err)
return err;
@@ -443,7 +446,7 @@ 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;

if (fc->no_flush)
@@ -506,7 +509,7 @@ 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);
@@ -830,7 +833,7 @@ 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);
@@ -973,7 +976,7 @@ static int fuse_readpages(struct file *file, struct address_space *mapping,
int err;

err = -EIO;
- if (is_bad_inode(inode))
+ if (fuse_is_bad(inode))
goto out;

data.file = file;
@@ -1569,7 +1572,7 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
struct file *file = iocb->ki_filp;
struct fuse_file *ff = file->private_data;

- if (is_bad_inode(file_inode(file)))
+ if (fuse_is_bad(file_inode(file)))
return -EIO;

if (!(ff->open_flags & FOPEN_DIRECT_IO))
@@ -1583,7 +1586,7 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
struct file *file = iocb->ki_filp;
struct fuse_file *ff = file->private_data;

- if (is_bad_inode(file_inode(file)))
+ if (fuse_is_bad(file_inode(file)))
return -EIO;

if (!(ff->open_flags & FOPEN_DIRECT_IO))
@@ -2133,7 +2136,7 @@ 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;
@@ -2911,7 +2914,7 @@ 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 d7cde216fc871..e3688312e9f1b 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -158,6 +158,8 @@ 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;
@@ -787,6 +789,16 @@ 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 f58ab84b09fb3..aa1d5cf1bc3a4 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -115,7 +115,7 @@ static void fuse_evict_inode(struct inode *inode)
fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup);
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));
}
@@ -306,7 +306,7 @@ 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 6a40f75a0d25e..70f685b61e3a5 100644
--- 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 20d052e08b3be..28fed52957707 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(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);

--
2.27.0