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/perf/util/mem-info.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 tools/perf/util/mem-info.c (limited to 'tools/perf/util/mem-info.c') diff --git a/tools/perf/util/mem-info.c b/tools/perf/util/mem-info.c new file mode 100644 index 000000000..d3efa9c13 --- /dev/null +++ b/tools/perf/util/mem-info.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include "mem-info.h" + +struct mem_info *mem_info__get(struct mem_info *mi) +{ + struct mem_info *result; + + if (RC_CHK_GET(result, mi)) + refcount_inc(mem_info__refcnt(mi)); + + return result; +} + +void mem_info__put(struct mem_info *mi) +{ + if (mi && refcount_dec_and_test(mem_info__refcnt(mi))) { + addr_map_symbol__exit(mem_info__iaddr(mi)); + addr_map_symbol__exit(mem_info__daddr(mi)); + RC_CHK_FREE(mi); + } else { + RC_CHK_PUT(mi); + } +} + +struct mem_info *mem_info__new(void) +{ + struct mem_info *result = NULL; + RC_STRUCT(mem_info) *mi = zalloc(sizeof(*mi)); + + if (ADD_RC_CHK(result, mi)) + refcount_set(mem_info__refcnt(result), 1); + + return result; +} + +struct mem_info *mem_info__clone(struct mem_info *mi) +{ + struct mem_info *result = mem_info__new(); + + if (result) { + addr_map_symbol__copy(mem_info__iaddr(result), mem_info__iaddr(mi)); + addr_map_symbol__copy(mem_info__daddr(result), mem_info__daddr(mi)); + mem_info__data_src(result)->val = mem_info__data_src(mi)->val; + } + + return result; +} -- cgit v1.3.1