From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 272B3DF43 for ; Sat, 23 Dec 2023 15:36:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NsOv68yv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FDA3C433C7; Sat, 23 Dec 2023 15:36:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1703345790; bh=Ho1EszqwI0wE1B1/PMEe80cbefmCuK5iTTKpuBzHd0I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NsOv68yv+cb3ou8kcwnUxC8c0MA2UhlsYmJxQdQa7xEJLYP/aTWReGaXvlfYHyTFA GMbpoTp5Hdmv2X43KDuzCFFeYpgaX7VocsElUwZwdD355df38wsWpAQtQBbJdjrt7+ T4fXwNWYOnNkAEhc1hhTRBvQycFlvHS09VDi8DCSpeyB8aQbnH/X4o/QKxeWoh7d86 1R+5AKjE7RrCj7hrK0VELBSv9MnLWVffjmEmZjxlbAZeeSyT/K/ZzJrN/yboOpsvhz +0+ktFxWt/iz1PH2fCvs+iWjL8zmDpj/Jf5vmGkzZ50LY0JDNLky6GepnoxRV46Tu4 o1uDUr2dFeMSw== Date: Sat, 23 Dec 2023 09:36:25 -0600 From: Eric Biggers To: Zhihao Cheng Cc: richard@nod.at, terrelln@fb.com, linux-fscrypt@vger.kernel.org, linux-mtd@lists.infradead.org Subject: Re: [PATCH v2 2/2] ubifs: ubifs_symlink: Fix memleak of inode->i_link in error path Message-ID: <20231223153625.GC901@quark.localdomain> References: <20231222085446.781838-1-chengzhihao1@huawei.com> <20231222085446.781838-3-chengzhihao1@huawei.com> Precedence: bulk X-Mailing-List: linux-fscrypt@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231222085446.781838-3-chengzhihao1@huawei.com> On Fri, Dec 22, 2023 at 04:54:46PM +0800, Zhihao Cheng wrote: > For error handling path in ubifs_symlink(), inode will be marked as > bad first, then iput() is invoked. If inode->i_link is initialized by > fscrypt_encrypt_symlink() in encryption scenario, inode->i_link won't > be freed by callchain ubifs_free_inode -> fscrypt_free_inode in error > handling path, because make_bad_inode() has changed 'inode->i_mode' as > 'S_IFREG'. > Following kmemleak is easy to be reproduced by injecting error in > ubifs_jnl_update() when doing symlink in encryption scenario: > unreferenced object 0xffff888103da3d98 (size 8): > comm "ln", pid 1692, jiffies 4294914701 (age 12.045s) > backtrace: > kmemdup+0x32/0x70 > __fscrypt_encrypt_symlink+0xed/0x1c0 > ubifs_symlink+0x210/0x300 [ubifs] > vfs_symlink+0x216/0x360 > do_symlinkat+0x11a/0x190 > do_syscall_64+0x3b/0xe0 > There are two ways fixing it: > 1. Remove make_bad_inode() in error handling path. We can do that > because ubifs_evict_inode() will do same processes for good > symlink inode and bad symlink inode, for inode->i_nlink checking > is before is_bad_inode(). > 2. Free inode->i_link before marking inode bad. > Method 2 is picked, it has less influence, personally, I think. > > Cc: stable@vger.kernel.org > Fixes: 2c58d548f570 ("fscrypt: cache decrypted symlink target in ->i_link") > Signed-off-by: Zhihao Cheng > Suggested-by: Eric Biggers > --- > fs/ubifs/dir.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c > index 3b13c648d490..e413a9cf8ee3 100644 > --- a/fs/ubifs/dir.c > +++ b/fs/ubifs/dir.c > @@ -1234,6 +1234,8 @@ static int ubifs_symlink(struct mnt_idmap *idmap, struct inode *dir, > dir_ui->ui_size = dir->i_size; > mutex_unlock(&dir_ui->ui_mutex); > out_inode: > + /* Free inode->i_link before inode is marked as bad. */ > + fscrypt_free_inode(inode); > make_bad_inode(inode); > iput(inode); > out_fname: Reviewed-by: Eric Biggers - Eric