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 34BA1631; Wed, 14 Aug 2024 00:50:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723596603; cv=none; b=VUliDyzQzG37SNAuwsu+25vYzJMd0hZHhODigtgX7bv7TcVie/ADRIgc2yjpuGlRguBfSZc5zzGuSlc9fKbd7lbncQMIHdtdMM7bH9bS5AkT4PEdSBOXQ3r5G6nGXOrJ7bTSSpXeyqF8ArPtHTJDAM5YxI/hr5YZxvgg8XJsdKA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723596603; c=relaxed/simple; bh=I32+sTObO1qHA580hNby1ngJWF5eI+mQSCNRkHDgNhA=; h=Date:To:From:Subject:Message-Id; b=HlSBbTKyWpdTGoo6QcustLoaPSppZhDQ4MysO2t6bGvLBMdn+2PRNEANqY1dsMA3pL2eRVF3/giXr1Ox1qazgbl4zhaDj8APnQqvExH4oCZEn10/8U/tEE07EEEXd68l3qYqotkAp06bjnsi2zbD0/6w6gcWJXR4ekUIJvWLLWc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=wIwB2lL/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="wIwB2lL/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9121FC32782; Wed, 14 Aug 2024 00:50:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1723596602; bh=I32+sTObO1qHA580hNby1ngJWF5eI+mQSCNRkHDgNhA=; h=Date:To:From:Subject:From; b=wIwB2lL/5vdLN3JxUM9BreLVaoNb271sZMAP/Wwb6xaVQfzU5PRoqVxtzW1MSNDTk ZCweGICPvmNKS4XcnpZarZlLK1h42OETK8i2gkaMte+pYcpRQAguUv4s+rejZ/Qzio KwLGardXIeB0tzCHPr6V7/WaeBgVFXy9itpcyaXc= Date: Tue, 13 Aug 2024 17:50:01 -0700 To: mm-commits@vger.kernel.org,viro@zeniv.linux.org.uk,stable@vger.kernel.org,lizhi.xu@windriver.com,jack@suse.cz,brauner@kernel.org,phillip@squashfs.org.uk,akpm@linux-foundation.org From: Andrew Morton Subject: + squashfs-sanity-check-symbolic-link-size.patch added to mm-hotfixes-unstable branch Message-Id: <20240814005002.9121FC32782@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: Squashfs: sanity check symbolic link size has been added to the -mm mm-hotfixes-unstable branch. Its filename is squashfs-sanity-check-symbolic-link-size.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/squashfs-sanity-check-symbolic-link-size.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Phillip Lougher Subject: Squashfs: sanity check symbolic link size Date: Sun, 11 Aug 2024 21:13:01 +0100 Syzkiller reports a "KMSAN: uninit-value in pick_link" bug. This is caused by an uninitialised page, which is ultimately caused by a corrupted symbolic link size read from disk. The reason why the corrupted symlink size causes an uninitialised page is due to the following sequence of events: 1. squashfs_read_inode() is called to read the symbolic link from disk. This assigns the corrupted value 3875536935 to inode->i_size. 2. Later squashfs_symlink_read_folio() is called, which assigns this corrupted value to the length variable, which being a signed int, overflows producing a negative number. 3. The following loop that fills in the page contents checks that the copied bytes is less than length, which being negative means the loop is skipped, producing an unitialised page. This patch adds a sanity check which checks that the symbolic link size is not larger than expected. Link: https://lkml.kernel.org/r/20240811201301.13076-1-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher Reported-by: Lizhi Xu Reported-by: syzbot+24ac24ff58dc5b0d26b9@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000a90e8c061e86a76b@google.com/ Cc: Al Viro Cc: Christian Brauner Cc: Jan Kara Cc: Phillip Lougher Cc: Signed-off-by: Andrew Morton --- fs/squashfs/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/squashfs/inode.c~squashfs-sanity-check-symbolic-link-size +++ a/fs/squashfs/inode.c @@ -279,8 +279,13 @@ int squashfs_read_inode(struct inode *in if (err < 0) goto failed_read; - set_nlink(inode, le32_to_cpu(sqsh_ino->nlink)); inode->i_size = le32_to_cpu(sqsh_ino->symlink_size); + if (inode->i_size > PAGE_SIZE) { + ERROR("Corrupted symlink\n"); + return -EINVAL; + } + + set_nlink(inode, le32_to_cpu(sqsh_ino->nlink)); inode->i_op = &squashfs_symlink_inode_ops; inode_nohighmem(inode); inode->i_data.a_ops = &squashfs_symlink_aops; _ Patches currently in -mm which might be from phillip@squashfs.org.uk are squashfs-sanity-check-symbolic-link-size.patch