From: Miklos Szeredi Date: Mon, 27 May 2024 13:44:48 +0000 (+0200) Subject: ovl: fix copy-up in tmpfile X-Git-Tag: v6.10-rc5~20^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=db03d39053a97d2f2a6baec025ebdacbab5886d2;p=thirdparty%2Fkernel%2Flinux.git ovl: fix copy-up in tmpfile Move ovl_copy_up() call outside of ovl_want_write()/ovl_drop_write() region, since copy up may also call ovl_want_write() resulting in recursive locking on sb->s_writers. Reported-and-tested-by: syzbot+85e58cdf5b3136471d4b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000f6865106191c3e58@google.com/ Fixes: 9a87907de359 ("ovl: implement tmpfile") Signed-off-by: Miklos Szeredi --- diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 116f542442ddd..ab65e98a1defd 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -1314,10 +1314,6 @@ static int ovl_create_tmpfile(struct file *file, struct dentry *dentry, int flags = file->f_flags | OVL_OPEN_FLAGS; int err; - err = ovl_copy_up(dentry->d_parent); - if (err) - return err; - old_cred = ovl_override_creds(dentry->d_sb); err = ovl_setup_cred_for_create(dentry, inode, mode, old_cred); if (err) @@ -1360,6 +1356,10 @@ static int ovl_tmpfile(struct mnt_idmap *idmap, struct inode *dir, if (!OVL_FS(dentry->d_sb)->tmpfile) return -EOPNOTSUPP; + err = ovl_copy_up(dentry->d_parent); + if (err) + return err; + err = ovl_want_write(dentry); if (err) return err;