From 1039bffd6ae9c75b42b7d148d6c1106134107b66 Mon Sep 17 00:00:00 2001 From: Xie Yuanbin Date: Tue, 28 Jul 2026 03:16:42 +0100 Subject: ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults 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 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) Reviewed-by: Linus Walleij Signed-off-by: Qi Xi Signed-off-by: Xie Yuanbin Signed-off-by: Russell King --- tools/perf/tests/demangle-java-test.c | 49 +++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 tools/perf/tests/demangle-java-test.c (limited to 'tools/perf/tests/demangle-java-test.c') diff --git a/tools/perf/tests/demangle-java-test.c b/tools/perf/tests/demangle-java-test.c new file mode 100644 index 000000000..0fb3e5a4a --- /dev/null +++ b/tools/perf/tests/demangle-java-test.c @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include "debug.h" +#include "symbol.h" +#include "tests.h" + +static int test__demangle_java(struct test_suite *test __maybe_unused, int subtest __maybe_unused) +{ + int ret = TEST_OK; + char *buf = NULL; + size_t i; + + struct { + const char *mangled, *demangled; + } test_cases[] = { + { "Ljava/lang/StringLatin1;equals([B[B)Z", + "java.lang.StringLatin1.equals(byte[], byte[])" }, + { "Ljava/util/zip/ZipUtils;CENSIZ([BI)J", + "java.util.zip.ZipUtils.CENSIZ(byte[], int)" }, + { "Ljava/util/regex/Pattern$BmpCharProperty;match(Ljava/util/regex/Matcher;ILjava/lang/CharSequence;)Z", + "java.util.regex.Pattern$BmpCharProperty.match(java.util.regex.Matcher, int, java.lang.CharSequence)" }, + { "Ljava/lang/AbstractStringBuilder;appendChars(Ljava/lang/String;II)V", + "java.lang.AbstractStringBuilder.appendChars(java.lang.String, int, int)" }, + { "Ljava/lang/Object;()V", + "java.lang.Object()" }, + }; + + for (i = 0; i < ARRAY_SIZE(test_cases); i++) { + buf = dso__demangle_sym(/*dso=*/NULL, /*kmodule=*/0, test_cases[i].mangled); + if (!buf) { + pr_debug("FAILED to demangle: \"%s\"\n \"%s\"\n", test_cases[i].mangled, + test_cases[i].demangled); + continue; + } + if (strcmp(buf, test_cases[i].demangled)) { + pr_debug("FAILED: %s: %s != %s\n", test_cases[i].mangled, + buf, test_cases[i].demangled); + ret = TEST_FAIL; + } + free(buf); + } + + return ret; +} + +DEFINE_SUITE("Demangle Java", demangle_java); -- cgit v1.3.1