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fuse: verify attributes

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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: d8a5ba4545 ("[PATCH] FUSE - core")
Cc: <stable@vger.kernel.org> # v2.6.14
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2019-11-12 11:49:04 +01:00
parent 31f4f5b495
commit eb59bd17d2
3 changed files with 19 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
fs/fuse/dir.c
View File

@ -248,7 +248,8 @@ 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);
@ -319,6 +320,12 @@ 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)
{
@ -350,7 +357,7 @@ 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,
@ -475,7 +482,8 @@ 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;
@ -583,7 +591,7 @@ 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)
@ -942,7 +950,8 @@ 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 {
@ -1563,7 +1572,8 @@ 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;

2
fs/fuse/fuse_i.h
View File

@ -989,6 +989,8 @@ 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?
*/

2
fs/fuse/readdir.c
View File

@ -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);