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/pstack.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) create mode 100644 tools/perf/util/pstack.c (limited to 'tools/perf/util/pstack.c') diff --git a/tools/perf/util/pstack.c b/tools/perf/util/pstack.c new file mode 100644 index 000000000..141ffa129 --- /dev/null +++ b/tools/perf/util/pstack.c @@ -0,0 +1,71 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Simple pointer stack + * + * (c) 2010 Arnaldo Carvalho de Melo + */ + +#include "pstack.h" +#include "debug.h" +#include +#include +#include +#include + +struct pstack { + unsigned short top; + unsigned short max_nr_entries; + void *entries[]; +}; + +struct pstack *pstack__new(unsigned short max_nr_entries) +{ + struct pstack *pstack = zalloc((sizeof(*pstack) + + max_nr_entries * sizeof(void *))); + if (pstack != NULL) + pstack->max_nr_entries = max_nr_entries; + return pstack; +} + +void pstack__delete(struct pstack *pstack) +{ + free(pstack); +} + +bool pstack__empty(const struct pstack *pstack) +{ + return pstack->top == 0; +} + +void pstack__remove(struct pstack *pstack, void *key) +{ + unsigned short i = pstack->top, last_index = pstack->top - 1; + + while (i-- != 0) { + if (pstack->entries[i] == key) { + if (i < last_index) + memmove(pstack->entries + i, + pstack->entries + i + 1, + (last_index - i) * sizeof(void *)); + --pstack->top; + return; + } + } + pr_err("%s: %p not on the pstack!\n", __func__, key); +} + +void pstack__push(struct pstack *pstack, void *key) +{ + if (pstack->top == pstack->max_nr_entries) { + pr_err("%s: top=%d, overflow!\n", __func__, pstack->top); + return; + } + pstack->entries[pstack->top++] = key; +} + +void *pstack__peek(struct pstack *pstack) +{ + if (pstack->top == 0) + return NULL; + return pstack->entries[pstack->top - 1]; +} -- cgit v1.3.1