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/pmu.l | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 tools/perf/util/pmu.l (limited to 'tools/perf/util/pmu.l') diff --git a/tools/perf/util/pmu.l b/tools/perf/util/pmu.l new file mode 100644 index 000000000..67b247be6 --- /dev/null +++ b/tools/perf/util/pmu.l @@ -0,0 +1,48 @@ +%option prefix="perf_pmu_" +%option reentrant +%option bison-bridge + +%{ +#include +#include +#include "pmu.h" +#include "pmu-bison.h" + +char *perf_pmu_get_text(yyscan_t yyscanner); +YYSTYPE *perf_pmu_get_lval(yyscan_t yyscanner); + +static int value(yyscan_t scanner, int base) +{ + YYSTYPE *yylval = perf_pmu_get_lval(scanner); + char *text = perf_pmu_get_text(scanner); + long num; + + errno = 0; + num = strtoul(text, NULL, base); + if (errno) + return PP_ERROR; + + yylval->num = num; + return PP_VALUE; +} + +%} + +num_dec [0-9]+ + +%% + +{num_dec} { return value(yyscanner, 10); } +config { return PP_CONFIG; } +- { return '-'; } +: { return ':'; } +, { return ','; } +. { ; } +\n { ; } + +%% + +int perf_pmu_wrap(void *scanner __maybe_unused) +{ + return 1; +} -- cgit v1.3.1