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/rlimit.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 tools/perf/util/rlimit.c (limited to 'tools/perf/util/rlimit.c') diff --git a/tools/perf/util/rlimit.c b/tools/perf/util/rlimit.c new file mode 100644 index 000000000..f857405fe --- /dev/null +++ b/tools/perf/util/rlimit.c @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: LGPL-2.1 */ + +#include +#include "util/debug.h" +#include "util/rlimit.h" +#include +#include + +/* + * Bump the memlock so that we can get bpf maps of a reasonable size, + * like the ones used with 'perf trace' and with 'perf test bpf', + * improve this to some specific request if needed. + */ +void rlimit__bump_memlock(void) +{ + struct rlimit rlim; + + if (getrlimit(RLIMIT_MEMLOCK, &rlim) == 0) { + rlim.rlim_cur *= 4; + rlim.rlim_max *= 4; + + if (setrlimit(RLIMIT_MEMLOCK, &rlim) < 0) { + rlim.rlim_cur /= 2; + rlim.rlim_max /= 2; + + if (setrlimit(RLIMIT_MEMLOCK, &rlim) < 0) + pr_debug("Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc\n"); + } + } +} + +bool rlimit__increase_nofile(enum rlimit_action *set_rlimit) +{ + int old_errno; + struct rlimit l; + + if (*set_rlimit < INCREASED_MAX) { + old_errno = errno; + + if (getrlimit(RLIMIT_NOFILE, &l) == 0) { + if (*set_rlimit == NO_CHANGE) { + l.rlim_cur = l.rlim_max; + } else { + l.rlim_cur = l.rlim_max + 1000; + l.rlim_max = l.rlim_cur; + } + if (setrlimit(RLIMIT_NOFILE, &l) == 0) { + (*set_rlimit) += 1; + errno = old_errno; + return true; + } + } + errno = old_errno; + } + + return false; +} -- cgit v1.3.1