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 --- tools/testing/radix-tree/regression4.c | 79 ++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) create mode 100644 tools/testing/radix-tree/regression4.c (limited to 'tools/testing/radix-tree/regression4.c') diff --git a/tools/testing/radix-tree/regression4.c b/tools/testing/radix-tree/regression4.c new file mode 100644 index 000000000..cf4e5aba6 --- /dev/null +++ b/tools/testing/radix-tree/regression4.c @@ -0,0 +1,79 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "regression.h" + +static pthread_barrier_t worker_barrier; +static int obj0, obj1; +static RADIX_TREE(mt_tree, GFP_KERNEL); + +static void *reader_fn(void *arg) +{ + int i; + void *entry; + + rcu_register_thread(); + pthread_barrier_wait(&worker_barrier); + + for (i = 0; i < 1000000; i++) { + rcu_read_lock(); + entry = radix_tree_lookup(&mt_tree, 0); + rcu_read_unlock(); + if (entry != &obj0) { + printf("iteration %d bad entry = %p\n", i, entry); + abort(); + } + } + + rcu_unregister_thread(); + + return NULL; +} + +static void *writer_fn(void *arg) +{ + int i; + + rcu_register_thread(); + pthread_barrier_wait(&worker_barrier); + + for (i = 0; i < 1000000; i++) { + radix_tree_insert(&mt_tree, 1, &obj1); + radix_tree_delete(&mt_tree, 1); + } + + rcu_unregister_thread(); + + return NULL; +} + +void regression4_test(void) +{ + pthread_t reader, writer; + + printv(1, "regression test 4 starting\n"); + + radix_tree_insert(&mt_tree, 0, &obj0); + pthread_barrier_init(&worker_barrier, NULL, 2); + + if (pthread_create(&reader, NULL, reader_fn, NULL) || + pthread_create(&writer, NULL, writer_fn, NULL)) { + perror("pthread_create"); + exit(1); + } + + if (pthread_join(reader, NULL) || pthread_join(writer, NULL)) { + perror("pthread_join"); + exit(1); + } + + printv(1, "regression test 4 passed\n"); +} -- cgit v1.3.1