From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 811C1436BC6; Tue, 21 Jul 2026 19:57:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784663862; cv=none; b=U2vydvX2z14GffNfm+EVUnzbyO3NdjsErBfjsQ9ic2QDCE+OvBwOBNfFVgbkQzcLz3QvxuAYaKrbx8Gl72UcQSaVuzycuk0K2QidmUP1Mk77tsSeIKPTQx4GgS+9ATUoaD3XHYMJQNAw0AVQDfcks6ulp29Wgw1KXXOTBVIRbtU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784663862; c=relaxed/simple; bh=XBjuDnhT4pA0l1b1v+2Lny030djbz8I8eezuud1bv1w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=G5zSpj21ArbOdaYsPIG+BvkYAbYeZznYDOnT6cKEWj5rXRk4K/nseL87mxpS36aETWi9uaIDUCZ1QP4oD8kCw5oqL6OcEYHQyAUzF7myLugoQ6KpErVIm/iuu5ncwNDtdMzYWP4q7ZoVudDGvUe3UQBamf7EO9/RQUSLy9sG9tM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Q7IIhrQO; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Q7IIhrQO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA4FE1F000E9; Tue, 21 Jul 2026 19:57:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784663861; bh=AQodMFzlmY7wKm+ZsOPGPqf1BtDYF6ToVt10PdeMPik=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Q7IIhrQOrJlE1JMoWWH0iT3lpEPj959th+V/sCY3XkGt5dZ1frXh9ffFihJG028Tr RnFmlTxZUDvHatATpOaPFM/D49E57DxXOvHsCkPIlWe4yMLU8qXzjDJxgzCIF/8v7U wTC7fjIdZMTjHsU0FgqeHjXsFlhQDSqs6hZbCi8g= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jaewon Yang , Linus Torvalds Subject: [PATCH 6.12 0984/1276] tpm: Make the TPM character devices non-seekable Date: Tue, 21 Jul 2026 17:23:47 +0200 Message-ID: <20260721152508.035897100@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152446.065700225@linuxfoundation.org> References: <20260721152446.065700225@linuxfoundation.org> User-Agent: quilt/0.69 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jaewon Yang commit f20d61c22bcaf172d6790b6500e3838e532e71c8 upstream. The TPM character devices expose a sequential command/response interface, but their open handlers leave FMODE_PREAD and FMODE_PWRITE enabled. After a command leaves a response pending, pread(fd, buf, 16, 0x1400) passes 0x1400 as *off to tpm_common_read(). The transfer length is bounded by response_length, but the offset is used unchecked when forming data_buffer + *off. A sufficiently large offset therefore causes an out-of-bounds heap read through copy_to_user() and, if the copy succeeds, an out-of-bounds zero-write through the following memset(). Positional I/O does not provide coherent semantics for this interface. An arbitrary pread offset cannot represent how much of a response has been consumed sequentially. The write callback always stores a command at the start of data_buffer, while pwrite() does not update file->f_pos and can leave the sequential read cursor stale. Call nonseekable_open() from both open handlers. This removes FMODE_PREAD and FMODE_PWRITE, causing positional reads and writes to fail with -ESPIPE before reaching the TPM callbacks, and explicitly marks the files non-seekable. Normal read() and write() continue to use the existing sequential f_pos cursor, leaving the response state machine unchanged. Tested on Linux 6.12 with KASAN and a swtpm TPM2 device: - sequential partial reads returned the complete response - pread() and preadv() with offset 0x1400 returned -ESPIPE - pwrite() and pwritev() with offset zero returned -ESPIPE - the pending response remained intact after the rejected operations - a subsequent normal command/response cycle completed normally - no KASAN report was produced. Fixes: 9488585b21be ("tpm: add support for partial reads") Link: https://lore.kernel.org/all/20260710090217.191289-1-yong010301@gmail.com/ Cc: stable@vger.kernel.org Signed-off-by: Jaewon Yang Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/char/tpm/tpm-dev.c | 2 +- drivers/char/tpm/tpmrm-dev.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/drivers/char/tpm/tpm-dev.c +++ b/drivers/char/tpm/tpm-dev.c @@ -36,7 +36,7 @@ static int tpm_open(struct inode *inode, tpm_common_open(file, chip, priv, NULL); - return 0; + return nonseekable_open(inode, file); out: clear_bit(0, &chip->is_open); --- a/drivers/char/tpm/tpmrm-dev.c +++ b/drivers/char/tpm/tpmrm-dev.c @@ -29,7 +29,7 @@ static int tpmrm_open(struct inode *inod tpm_common_open(file, chip, &priv->priv, &priv->space); - return 0; + return nonseekable_open(inode, file); } static int tpmrm_release(struct inode *inode, struct file *file)