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 0CC0518B46D; Tue, 10 Sep 2024 09:40:28 +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=1725961229; cv=none; b=agbzc6Ox+7Ena76/MoWaz4wZ2k9EUwRE2gXxpQP+TBFWPMoElrc3Qytb/4Md8c7NcP/vICl0xR5sP0IfCkYYYXU9TIMK39NP2GBzQ8sUUZKjHQox+PHLlCn71t+IMflU5vyM9NdcJZwT+WmssUuwCMYgSZvbXNKIYcuvdL11l0M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725961229; c=relaxed/simple; bh=Z0tWtSHixfzzoPjijwIaZsbtS/UAC3I60wltV7XkRUY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XFr2nITlWNJf7Oysh8p2rBTkaA5jYldBpGTwTBECkXFBcIm4nV79hp1J8BZku0RbfvXEzktoKT8mTwpKax5C6wqeCGPizoMNUJ9GvPLiN7Fac0ZDiJdpYKfUcdmtf813wDmTgPBJvitBhJtTEmsfGMqa4QdV2ZOm2qUqVes4d2I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VY4gyOS+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="VY4gyOS+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BB34C4CEC3; Tue, 10 Sep 2024 09:40:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1725961228; bh=Z0tWtSHixfzzoPjijwIaZsbtS/UAC3I60wltV7XkRUY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VY4gyOS+jvjYlQUFmRPpZQqqIKwnwwfTYoZ+wj6bDnCNSwX8TGmoKAIzkhEFJIoew BuKtu0t72LqAWcnYSKM30KEacUo0Kza5R1Nryv7kkHkqCf9/UA1qo8wycA4qw2RMo7 Q6am2SomuLW/yUoToiUhP/k21c31BHvSc6HLtMzw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Phillip Lougher , Lizhi Xu , syzbot+24ac24ff58dc5b0d26b9@syzkaller.appspotmail.com, Christian Brauner , Sasha Levin Subject: [PATCH 4.19 70/96] Squashfs: sanity check symbolic link size Date: Tue, 10 Sep 2024 11:32:12 +0200 Message-ID: <20240910092544.629785574@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240910092541.383432924@linuxfoundation.org> References: <20240910092541.383432924@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Phillip Lougher [ Upstream commit 810ee43d9cd245d138a2733d87a24858a23f577d ] 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 uninitialised page. This patch adds a sanity check which checks that the symbolic link size is not larger than expected. -- Signed-off-by: Phillip Lougher Link: https://lore.kernel.org/r/20240811232821.13903-1-phillip@squashfs.org.uk Reported-by: Lizhi Xu Reported-by: syzbot+24ac24ff58dc5b0d26b9@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000a90e8c061e86a76b@google.com/ V2: fix spelling mistake. Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/squashfs/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c index e9793b1e49a5..89ac1c6de97b 100644 --- a/fs/squashfs/inode.c +++ b/fs/squashfs/inode.c @@ -289,8 +289,13 @@ int squashfs_read_inode(struct inode *inode, long long ino) 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; -- 2.43.0