[PATCH 4.19 198/243] fuse: verify attributes

Greg Kroah-Hartman
2019-12-11T15:24:23Z

From: Miklos Szeredi <mszeredi@redhat.com>

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/fuse/dir.c | 24 +++++++++++++++++-------
fs/fuse/fuse_i.h | 2 ++
2 files changed, 19 insertions(+), 7 deletions(-)

--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -234,7 +234,8 @@ static int fuse_dentry_revalidate(struct
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);
@@ -297,6 +298,12 @@ 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)
{
@@ -328,7 +335,7 @@ int fuse_lookup_name(struct super_block
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,
@@ -451,7 +458,8 @@ static int fuse_create_open(struct inode
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;
@@ -558,7 +566,7 @@ static int create_new_entry(struct fuse_
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)
@@ -918,7 +926,8 @@ static int fuse_do_getattr(struct inode
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 {
@@ -1230,7 +1239,7 @@ static int fuse_direntplus_link(struct f

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);
@@ -1707,7 +1716,8 @@ int fuse_do_setattr(struct dentry *dentr
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;
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -909,6 +909,8 @@ void fuse_ctl_remove_conn(struct fuse_co
*/
int fuse_valid_type(int m);

+bool fuse_invalid_attr(struct fuse_attr *attr);
+
/**
* Is current process allowed to perform filesystem operation?
*/