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/perf-read-vdso.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 tools/perf/perf-read-vdso.c (limited to 'tools/perf/perf-read-vdso.c') diff --git a/tools/perf/perf-read-vdso.c b/tools/perf/perf-read-vdso.c new file mode 100644 index 000000000..aaa5210ea --- /dev/null +++ b/tools/perf/perf-read-vdso.c @@ -0,0 +1,35 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +#define VDSO__MAP_NAME "[vdso]" + +/* + * Include definition of find_map() also used in util/vdso.c for + * building perf. + */ +#include "util/find-map.c" + +int main(void) +{ + void *start, *end; + size_t size, written; + + if (find_map(&start, &end, VDSO__MAP_NAME)) + return 1; + + size = end - start; + + while (size) { + written = fwrite(start, 1, size, stdout); + if (!written) + return 1; + start += written; + size -= written; + } + + if (fflush(stdout)) + return 1; + + return 0; +} -- cgit v1.3.1