From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- drivers/char/tpm/tpmrm-dev.c | 54 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 drivers/char/tpm/tpmrm-dev.c (limited to 'drivers/char/tpm/tpmrm-dev.c') diff --git a/drivers/char/tpm/tpmrm-dev.c b/drivers/char/tpm/tpmrm-dev.c new file mode 100644 index 000000000..19e8f2779 --- /dev/null +++ b/drivers/char/tpm/tpmrm-dev.c @@ -0,0 +1,54 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2017 James.Bottomley@HansenPartnership.com + */ +#include +#include "tpm-dev.h" + +struct tpmrm_priv { + struct file_priv priv; + struct tpm_space space; +}; + +static int tpmrm_open(struct inode *inode, struct file *file) +{ + struct tpm_chip *chip; + struct tpmrm_priv *priv; + int rc; + + chip = container_of(inode->i_cdev, struct tpm_chip, cdevs); + priv = kzalloc_obj(*priv); + if (priv == NULL) + return -ENOMEM; + + rc = tpm2_init_space(&priv->space, TPM2_SPACE_BUFFER_SIZE); + if (rc) { + kfree(priv); + return -ENOMEM; + } + + tpm_common_open(file, chip, &priv->priv, &priv->space); + + return nonseekable_open(inode, file); +} + +static int tpmrm_release(struct inode *inode, struct file *file) +{ + struct file_priv *fpriv = file->private_data; + struct tpmrm_priv *priv = container_of(fpriv, struct tpmrm_priv, priv); + + tpm_common_release(file, fpriv); + tpm2_del_space(fpriv->chip, &priv->space); + kfree(priv); + + return 0; +} + +const struct file_operations tpmrm_fops = { + .owner = THIS_MODULE, + .open = tpmrm_open, + .read = tpm_common_read, + .write = tpm_common_write, + .poll = tpm_common_poll, + .release = tpmrm_release, +}; -- cgit v1.3.1