ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faultsgrafted

When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
a user fault may trigger show_pte() without any lock.
If another thread in the same process concurrently calls munmap(),
the page table pages may be freed while show_pte() is still traversing
them, causing a use-after-free in show_pte().

If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table
of PMD are freed when show_pte() is running.

Acquire mmap_write_lock() around show_pte() for user faults to fix the
contention.

For user faults, additionally restrict that show_pte() is called only
when the addr is a user-space address (addr < TASK_SIZE). This is because
the lock of tsk->mm only protects the virtual memory of user address space,
furthermore, dumping the page tables of a kernel-space address for user
faults is unnecessary and may have security implications.

Keep everything unchanged for kernel faults, because the kernel is
already in the "oops" state, acquiring a lock may risk a deadlock.

Co-developed-by: Qi Xi <xiqi2@huawei.com>

Fixes: 6d021b724481 ("ARM: dump pgd, pmd and pte states on unhandled data abort faults")
Link: https://lore.kernel.org/20260716014022.2823-1-xieyuanbin1@huawei.com
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Xie Yuanbin <xieyuanbin1@huawei.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 106 insertions, 0 deletions

diff --git a/tools/perf/Build b/tools/perf/Build
new file mode 100644
index 000000000..e18c80a5c
--- /dev/null
+++ b/tools/perf/Build
@@ -0,0 +1,106 @@
+perf-bench-y += builtin-bench.o
+perf-y += builtin-annotate.o
+perf-y += builtin-check.o
+perf-y += builtin-config.o
+perf-y += builtin-diff.o
+perf-y += builtin-evlist.o
+perf-y += builtin-ftrace.o
+perf-y += builtin-help.o
+perf-y += builtin-buildid-list.o
+perf-y += builtin-buildid-cache.o
+perf-y += builtin-kallsyms.o
+perf-y += builtin-list.o
+perf-y += builtin-record.o
+perf-y += builtin-report.o
+perf-y += builtin-stat.o
+perf-y += builtin-top.o
+perf-y += builtin-script.o
+perf-y += builtin-kvm.o
+perf-y += builtin-inject.o
+perf-y += builtin-mem.o
+perf-y += builtin-data.o
+perf-y += builtin-version.o
+perf-y += builtin-c2c.o
+perf-y += builtin-daemon.o
+
+perf-$(CONFIG_LIBTRACEEVENT) += builtin-kmem.o
+perf-$(CONFIG_LIBTRACEEVENT) += builtin-kwork.o
+perf-$(CONFIG_LIBTRACEEVENT) += builtin-lock.o
+perf-$(CONFIG_LIBTRACEEVENT) += builtin-sched.o
+perf-$(CONFIG_LIBTRACEEVENT) += builtin-timechart.o
+
+ifeq ($(CONFIG_LIBTRACEEVENT),y)
+  perf-$(CONFIG_TRACE) += builtin-trace.o
+  perf-$(CONFIG_TRACE) += trace/beauty/
+endif
+
+perf-util-y += trace/beauty/
+
+perf-$(CONFIG_LIBELF) += builtin-probe.o
+
+perf-bench-y += bench/
+perf-test-y += tests/
+
+perf-y += perf.o
+
+paths += -DPERF_HTML_PATH="BUILD_STR($(htmldir_SQ))"
+paths += -DPERF_INFO_PATH="BUILD_STR($(infodir_SQ))"
+paths += -DPERF_MAN_PATH="BUILD_STR($(mandir_SQ))"
+
+CFLAGS_builtin-help.o      += $(paths)
+CFLAGS_builtin-timechart.o += $(paths)
+CFLAGS_perf.o              += -DPERF_HTML_PATH="BUILD_STR($(htmldir_SQ))"	\
+			      -DPERF_EXEC_PATH="BUILD_STR($(perfexecdir_SQ))"	\
+			      -DPREFIX="BUILD_STR($(prefix_SQ))"
+CFLAGS_builtin-trace.o	   += -DSTRACE_GROUPS_DIR="BUILD_STR($(STRACE_GROUPS_DIR_SQ))"
+CFLAGS_builtin-report.o	   += -DTIPDIR="BUILD_STR($(tipdir_SQ))"
+CFLAGS_builtin-report.o	   += -DDOCDIR="BUILD_STR($(srcdir_SQ)/Documentation)"
+
+perf-util-y += util/
+perf-util-y += arch/
+perf-y += arch/
+perf-test-y += arch/
+perf-ui-y += ui/
+perf-util-y += scripts/
+
+gtk-y += ui/gtk/
+
+ifdef SHELLCHECK
+  SHELL_TESTS := $(wildcard *.sh)
+  SHELL_TEST_LOGS := $(SHELL_TESTS:%=%.shellcheck_log)
+else
+  SHELL_TESTS :=
+  SHELL_TEST_LOGS :=
+endif
+
+$(OUTPUT)%.shellcheck_log: %
+	$(call rule_mkdir)
+	$(Q)$(call echo-cmd,test)$(SHELLCHECK) "$<" > $@ || (cat $@ && rm $@ && false)
+
+perf-y += $(SHELL_TEST_LOGS)
+
+ifdef MYPY
+  PY_TESTS := $(shell find python -type f -name '*.py')
+  MYPY_TEST_LOGS := $(PY_TESTS:python/%=python/%.mypy_log)
+else
+  MYPY_TEST_LOGS :=
+endif
+
+$(OUTPUT)%.mypy_log: %
+	$(call rule_mkdir)
+	$(Q)$(call echo-cmd,test)mypy "$<" > $@ || (cat $@ && rm $@ && false)
+
+perf-y += $(MYPY_TEST_LOGS)
+
+ifdef PYLINT
+  PY_TESTS := $(shell find python -type f -name '*.py')
+  PYLINT_TEST_LOGS := $(PY_TESTS:python/%=python/%.pylint_log)
+else
+  PYLINT_TEST_LOGS :=
+endif
+
+$(OUTPUT)%.pylint_log: %
+	$(call rule_mkdir)
+	$(Q)$(call echo-cmd,test)pylint "$<" > $@ || (cat $@ && rm $@ && false)
+
+perf-y += $(PYLINT_TEST_LOGS)