In
0ee50b47532a ("namei: change filename_parentat() calling
conventions"), filename_parentat() was made to always call putname() on
the filename before returning, and kern_path_locked() was migrated to
this calling convention. However, kern_path_locked() uses the "last"
parameter to lookup and potentially create a new dentry. The last
parameter contains the last component of the path and points within the
filename, which was recently freed at the end of filename_parentat().
Thus, when kern_path_locked() calls __lookup_hash(), it is using the
filename after it has already been freed.
In other words, these calling conventions had been wrong for the
only remaining caller of filename_parentat(). Everything else
is using __filename_parentat(), which does not drop the reference;
so should kern_path_locked().
Switch kern_path_locked() to use of __filename_parentat() and move
getting/dropping struct filename into wrapper. Remove filename_parentat(),
now that we have no remaining callers.
Fixes:
0ee50b47532a ("namei: change filename_parentat() calling conventions")
Link: https://lore.kernel.org/linux-fsdevel/YS9D4AlEsaCxLFV0@infradead.org/
Link: https://lore.kernel.org/linux-fsdevel/YS+csMTV2tTXKg3s@zeniv-ca.linux.org.uk/
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: syzbot+fb0d60a179096e8c2731@syzkaller.appspotmail.com
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Co-authored-by: Dmitry Kadashev <dkadashev@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
+/* Note: this does not consume "name" */
static int __filename_parentat(int dfd, struct filename *name,
static int __filename_parentat(int dfd, struct filename *name,
- unsigned int flags, struct path *parent,
- struct qstr *last, int *type)
+ unsigned int flags, struct path *parent,
+ struct qstr *last, int *type)
{
int retval;
struct nameidata nd;
{
int retval;
struct nameidata nd;
-static int filename_parentat(int dfd, struct filename *name,
- unsigned int flags, struct path *parent,
- struct qstr *last, int *type)
-{
- int retval = __filename_parentat(dfd, name, flags, parent, last, type);
-
- putname(name);
- return retval;
-}
-
/* does lookup, returns the object with parent locked */
/* does lookup, returns the object with parent locked */
-struct dentry *kern_path_locked(const char *name, struct path *path)
+static struct dentry *__kern_path_locked(struct filename *name, struct path *path)
{
struct dentry *d;
struct qstr last;
int type, error;
{
struct dentry *d;
struct qstr last;
int type, error;
- error = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path,
- &last, &type);
+ error = __filename_parentat(AT_FDCWD, name, 0, path, &last, &type);
if (error)
return ERR_PTR(error);
if (unlikely(type != LAST_NORM)) {
if (error)
return ERR_PTR(error);
if (unlikely(type != LAST_NORM)) {
+struct dentry *kern_path_locked(const char *name, struct path *path)
+{
+ struct filename *filename = getname_kernel(name);
+ struct dentry *res = __kern_path_locked(filename, path);
+
+ putname(filename);
+ return res;
+}
+
int kern_path(const char *name, unsigned int flags, struct path *path)
{
return filename_lookup(AT_FDCWD, getname_kernel(name),
int kern_path(const char *name, unsigned int flags, struct path *path)
{
return filename_lookup(AT_FDCWD, getname_kernel(name),