release/5.2.30/fuse-verify-attributes.patch

From 8b07e294af44840175eb11fe6f86d1f18a7f8c4b Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Tue, 12 Nov 2019 11:49:04 +0100
Subject: [PATCH] fuse: verify attributes

commit eb59bd17d2fa6e5e84fba61a5ebdea984222e6d5 upstream.

If a filesystem returns negative inode sizes, future reads on the file were
causing the cpu to spin on truncate_pagecache.

Create a helper to validate the attributes.  This now does two things:

 - check the file mode
 - check if the file size fits in i_size without overflowing

Reported-by: Arijit Banerjee <arijit@rubrik.com>
Fixes: d8a5ba45457e ("[PATCH] FUSE - core")
Cc: <stable@vger.kernel.org> # v2.6.14
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index f57d2449b7a9..2d417bf778ef 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -214,7 +214,8 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
 		kfree(forget);
 		if (ret == -ENOMEM)
 			goto out;
-		if (ret || (outarg.attr.mode ^ inode->i_mode) & S_IFMT)
+		if (ret || fuse_invalid_attr(&outarg.attr) ||
+		    (outarg.attr.mode ^ inode->i_mode) & S_IFMT)
 			goto invalid;
 
 		forget_all_cached_acls(inode);
@@ -272,6 +273,12 @@ int fuse_valid_type(int m)
 		S_ISBLK(m) || S_ISFIFO(m) || S_ISSOCK(m);
 }
 
+bool fuse_invalid_attr(struct fuse_attr *attr)
+{
+	return !fuse_valid_type(attr->mode) ||
+		attr->size > LLONG_MAX;
+}
+
 int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name,
 		     struct fuse_entry_out *outarg, struct inode **inode)
 {
@@ -303,7 +310,7 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name
 	err = -EIO;
 	if (!outarg->nodeid)
 		goto out_put_forget;
-	if (!fuse_valid_type(outarg->attr.mode))
+	if (fuse_invalid_attr(&outarg->attr))
 		goto out_put_forget;
 
 	*inode = fuse_iget(sb, outarg->nodeid, outarg->generation,
@@ -427,7 +434,8 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
 		goto out_free_ff;
 
 	err = -EIO;
-	if (!S_ISREG(outentry.attr.mode) || invalid_nodeid(outentry.nodeid))
+	if (!S_ISREG(outentry.attr.mode) || invalid_nodeid(outentry.nodeid) ||
+	    fuse_invalid_attr(&outentry.attr))
 		goto out_free_ff;
 
 	ff->fh = outopen.fh;
@@ -535,7 +543,7 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args,
 		goto out_put_forget_req;
 
 	err = -EIO;
-	if (invalid_nodeid(outarg.nodeid))
+	if (invalid_nodeid(outarg.nodeid) || fuse_invalid_attr(&outarg.attr))
 		goto out_put_forget_req;
 
 	if ((outarg.attr.mode ^ mode) & S_IFMT)
@@ -895,7 +903,8 @@ static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
 	args.out.args[0].value = &outarg;
 	err = fuse_simple_request(fc, &args);
 	if (!err) {
-		if ((inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
+		if (fuse_invalid_attr(&outarg.attr) ||
+		    (inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
 			make_bad_inode(inode);
 			err = -EIO;
 		} else {
@@ -1518,7 +1527,8 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 		goto error;
 	}
 
-	if ((inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
+	if (fuse_invalid_attr(&outarg.attr) ||
+	    (inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
 		make_bad_inode(inode);
 		err = -EIO;
 		goto error;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 89bdc41e0d86..28ba17462325 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1008,6 +1008,8 @@ void fuse_ctl_remove_conn(struct fuse_conn *fc);
  */
 int fuse_valid_type(int m);
 
+bool fuse_invalid_attr(struct fuse_attr *attr);
+
 /**
  * Is current process allowed to perform filesystem operation?
  */
diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
index b2da3de6a78e..656afd035e21 100644
--- a/fs/fuse/readdir.c
+++ b/fs/fuse/readdir.c
@@ -184,7 +184,7 @@ static int fuse_direntplus_link(struct file *file,
 
 	if (invalid_nodeid(o->nodeid))
 		return -EIO;
-	if (!fuse_valid_type(o->attr.mode))
+	if (fuse_invalid_attr(&o->attr))
 		return -EIO;
 
 	fc = get_fuse_conn(dir);
-- 
2.7.4