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 --- include/net/dsa_stubs.h | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 include/net/dsa_stubs.h (limited to 'include/net/dsa_stubs.h') diff --git a/include/net/dsa_stubs.h b/include/net/dsa_stubs.h new file mode 100644 index 000000000..6f384897f --- /dev/null +++ b/include/net/dsa_stubs.h @@ -0,0 +1,48 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * include/net/dsa_stubs.h - Stubs for the Distributed Switch Architecture framework + */ + +#include +#include +#include +#include + +#if IS_ENABLED(CONFIG_NET_DSA) + +extern const struct dsa_stubs *dsa_stubs; + +struct dsa_stubs { + int (*conduit_hwtstamp_validate)(struct net_device *dev, + const struct kernel_hwtstamp_config *config, + struct netlink_ext_ack *extack); +}; + +static inline int dsa_conduit_hwtstamp_validate(struct net_device *dev, + const struct kernel_hwtstamp_config *config, + struct netlink_ext_ack *extack) +{ + if (!netdev_uses_dsa(dev)) + return 0; + + /* rtnl_lock() is a sufficient guarantee, because as long as + * netdev_uses_dsa() returns true, the dsa_core module is still + * registered, and so, dsa_unregister_stubs() couldn't have run. + * For netdev_uses_dsa() to start returning false, it would imply that + * dsa_conduit_teardown() has executed, which requires rtnl_lock(). + */ + ASSERT_RTNL(); + + return dsa_stubs->conduit_hwtstamp_validate(dev, config, extack); +} + +#else + +static inline int dsa_conduit_hwtstamp_validate(struct net_device *dev, + const struct kernel_hwtstamp_config *config, + struct netlink_ext_ack *extack) +{ + return 0; +} + +#endif -- cgit v1.3.1