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 5D19143901B; Tue, 21 Jul 2026 22:21:21 +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=1784672482; cv=none; b=fBOhQFRiV01BS2RlFkMgi9zuB55Fas1besNngHioCDlg/PVz6A4ce+i55I9Xxw6C/taPfxiACpZc3146VB2FmcnuYcU0pNcKTkgmIXPEmU9sE27kLCpzlmG/xJE8aKw9TE3+KgVmG84l6j2Z1qqhgpeOKUdx8qFPMHOFEJrMr5A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784672482; c=relaxed/simple; bh=wmOFr6o3uNHssbkrYe2O8cxFJFnYoPasQVpFPuHePG0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c76zU/oM1sjHQh6WyMTPUQJvETlZ9sdHk8YMhvKy7f33EUm0tD1Un3FqD0j5DHwEPzmOa/Jcg9ITWYzyd/tSodCQvGXaeCqu9V7GzAHcwyNWAj54Ct97A2gfTOq62JT5oa2w+BlCxQ5YAikf/CN40DHQKRmn3HV+6P3EnRNi/fg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=esrdIXbO; 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="esrdIXbO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C2E761F00A3A; Tue, 21 Jul 2026 22:21:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784672481; bh=bGRaW5krzIHu5OqvAwDoRUr6ZUs8xC+Ywa4kytBbHJk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=esrdIXbOf72mL1mOFCic9yQNO7aSKAi7vAhiFQnBJ54jPQ4vwHAssM2OMvii1bA+a Q7J0xY75yk95uTwVQmph9kMUHxhMS1GVC9TVzS7jX9z6mTfZ2FD8t6yuJ7EmBnPnCr Qrckx7vuH6TsW34ngUbFbE0S4745AA3rB5xhzOsw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jaewon Yang , Linus Torvalds Subject: [PATCH 5.15 642/843] tpm: Make the TPM character devices non-seekable Date: Tue, 21 Jul 2026 17:24:37 +0200 Message-ID: <20260721152420.508041500@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152405.946368001@linuxfoundation.org> References: <20260721152405.946368001@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 5.15-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)