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/regression3.c | 95 ++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) create mode 100644 tools/testing/radix-tree/regression3.c (limited to 'tools/testing/radix-tree/regression3.c') diff --git a/tools/testing/radix-tree/regression3.c b/tools/testing/radix-tree/regression3.c new file mode 100644 index 000000000..9f9a3b280 --- /dev/null +++ b/tools/testing/radix-tree/regression3.c @@ -0,0 +1,95 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Regression3 + * Description: + * Helper radix_tree_iter_retry resets next_index to the current index. + * In following radix_tree_next_slot current chunk size becomes zero. + * This isn't checked and it tries to dereference null pointer in slot. + * + * Helper radix_tree_iter_resume reset slot to NULL and next_index to index + 1, + * for tagger iteraction it also must reset cached tags in iterator to abort + * next radix_tree_next_slot and go to slow-path into radix_tree_next_chunk. + * + * Running: + * This test should run to completion immediately. The above bug would + * cause it to segfault. + * + * Upstream commit: + * Not yet + */ +#include +#include +#include +#include +#include +#include + +#include "regression.h" + +void regression3_test(void) +{ + RADIX_TREE(root, GFP_KERNEL); + void *ptr0 = (void *)4ul; + void *ptr = (void *)8ul; + struct radix_tree_iter iter; + void **slot; + bool first; + + printv(1, "running regression test 3 (should take milliseconds)\n"); + + radix_tree_insert(&root, 0, ptr0); + radix_tree_tag_set(&root, 0, 0); + + first = true; + radix_tree_for_each_tagged(slot, &root, &iter, 0, 0) { + printv(2, "tagged %ld %p\n", iter.index, *slot); + if (first) { + radix_tree_insert(&root, 1, ptr); + radix_tree_tag_set(&root, 1, 0); + first = false; + } + if (radix_tree_deref_retry(*slot)) { + printv(2, "retry at %ld\n", iter.index); + slot = radix_tree_iter_retry(&iter); + continue; + } + } + radix_tree_delete(&root, 1); + + first = true; + radix_tree_for_each_slot(slot, &root, &iter, 0) { + printv(2, "slot %ld %p\n", iter.index, *slot); + if (first) { + radix_tree_insert(&root, 1, ptr); + first = false; + } + if (radix_tree_deref_retry(*slot)) { + printv(2, "retry at %ld\n", iter.index); + slot = radix_tree_iter_retry(&iter); + continue; + } + } + + radix_tree_for_each_slot(slot, &root, &iter, 0) { + printv(2, "slot %ld %p\n", iter.index, *slot); + if (!iter.index) { + printv(2, "next at %ld\n", iter.index); + slot = radix_tree_iter_resume(slot, &iter); + } + } + + radix_tree_tag_set(&root, 0, 0); + radix_tree_tag_set(&root, 1, 0); + radix_tree_for_each_tagged(slot, &root, &iter, 0, 0) { + printv(2, "tagged %ld %p\n", iter.index, *slot); + if (!iter.index) { + printv(2, "next at %ld\n", iter.index); + slot = radix_tree_iter_resume(slot, &iter); + } + } + + radix_tree_delete(&root, 0); + radix_tree_delete(&root, 1); + + printv(1, "regression test 3 passed\n"); +} -- cgit v1.3.1