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/fncache.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 tools/perf/util/fncache.c (limited to 'tools/perf/util/fncache.c') diff --git a/tools/perf/util/fncache.c b/tools/perf/util/fncache.c new file mode 100644 index 000000000..bf9559c55 --- /dev/null +++ b/tools/perf/util/fncache.c @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Manage a cache of file names' existence */ +#include +#include +#include +#include +#include +#include "fncache.h" +#include "hashmap.h" + +static struct hashmap *fncache; + +static size_t fncache__hash(long key, void *ctx __maybe_unused) +{ + return str_hash((const char *)key); +} + +static bool fncache__equal(long key1, long key2, void *ctx __maybe_unused) +{ + return strcmp((const char *)key1, (const char *)key2) == 0; +} + +static void fncache__init(void) +{ + fncache = hashmap__new(fncache__hash, fncache__equal, /*ctx=*/NULL); +} + +static struct hashmap *fncache__get(void) +{ + static pthread_once_t fncache_once = PTHREAD_ONCE_INIT; + + pthread_once(&fncache_once, fncache__init); + + return fncache; +} + +static bool lookup_fncache(const char *name, bool *res) +{ + long val; + + if (!hashmap__find(fncache__get(), name, &val)) + return false; + + *res = (val != 0); + return true; +} + +static void update_fncache(const char *name, bool res) +{ + char *old_key = NULL, *key = strdup(name); + + if (key) { + hashmap__set(fncache__get(), key, res, &old_key, /*old_value*/NULL); + free(old_key); + } +} + +/* No LRU, only use when bounded in some other way. */ +bool file_available(const char *name) +{ + bool res; + + if (lookup_fncache(name, &res)) + return res; + res = access(name, R_OK) == 0; + update_fncache(name, res); + return res; +} -- cgit v1.3.1