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/bench/futex.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 tools/perf/bench/futex.c (limited to 'tools/perf/bench/futex.c') diff --git a/tools/perf/bench/futex.c b/tools/perf/bench/futex.c new file mode 100644 index 000000000..1968c9d00 --- /dev/null +++ b/tools/perf/bench/futex.c @@ -0,0 +1,64 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include + +#include "futex.h" + +#ifndef PR_FUTEX_HASH +#define PR_FUTEX_HASH 78 +# define PR_FUTEX_HASH_SET_SLOTS 1 +# define PR_FUTEX_HASH_GET_SLOTS 2 +#endif // PR_FUTEX_HASH + +void futex_set_nbuckets_param(struct bench_futex_parameters *params) +{ + int ret; + + if (params->nbuckets < 0) + return; + + ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets, 0); + if (ret) { + printf("Requesting %d hash buckets failed: %d/%m\n", + params->nbuckets, ret); + err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)"); + } +} + +void futex_print_nbuckets(struct bench_futex_parameters *params) +{ + char *futex_hash_mode; + int ret; + + ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_SLOTS); + if (params->nbuckets >= 0) { + if (ret != params->nbuckets) { + if (ret < 0) { + printf("Can't query number of buckets: %m\n"); + err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)"); + } + printf("Requested number of hash buckets does not currently used.\n"); + printf("Requested: %d in usage: %d\n", params->nbuckets, ret); + err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)"); + } + if (params->nbuckets == 0) + ret = asprintf(&futex_hash_mode, "Futex hashing: global hash"); + else + ret = asprintf(&futex_hash_mode, "Futex hashing: %d hash buckets", + params->nbuckets); + } else { + if (ret <= 0) { + ret = asprintf(&futex_hash_mode, "Futex hashing: global hash"); + } else { + ret = asprintf(&futex_hash_mode, "Futex hashing: auto resized to %d buckets", + ret); + } + } + if (ret < 0) + err(EXIT_FAILURE, "ENOMEM, futex_hash_mode"); + printf("%s\n", futex_hash_mode); + free(futex_hash_mode); +} -- cgit v1.3.1