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/util/string2.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 tools/perf/util/string2.h (limited to 'tools/perf/util/string2.h') diff --git a/tools/perf/util/string2.h b/tools/perf/util/string2.h new file mode 100644 index 000000000..4c8bff47c --- /dev/null +++ b/tools/perf/util/string2.h @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef PERF_STRING_H +#define PERF_STRING_H + +#include +#include +#include // pid_t +#include +#include + +extern const char *graph_dotted_line; +extern const char *dots; + +s64 perf_atoll(const char *str); +bool strglobmatch(const char *str, const char *pat); +bool strglobmatch_nocase(const char *str, const char *pat); +bool strlazymatch(const char *str, const char *pat); +static inline bool strisglob(const char *str) +{ + return strpbrk(str, "*?[") != NULL; +} +int strtailcmp(const char *s1, const char *s2); + +char *asprintf_expr_inout_ints(const char *var, bool in, size_t nints, int *ints); + +static inline char *asprintf_expr_in_ints(const char *var, size_t nints, int *ints) +{ + return asprintf_expr_inout_ints(var, true, nints, ints); +} + +static inline char *asprintf_expr_not_in_ints(const char *var, size_t nints, int *ints) +{ + return asprintf_expr_inout_ints(var, false, nints, ints); +} + +char *asprintf__tp_filter_pids(size_t npids, pid_t *pids); + +char *strpbrk_esc(char *str, const char *stopset); +char *strdup_esc(const char *str); +char *strpbrk_esq(char *str, const char *stopset); +char *strdup_esq(const char *str); + +unsigned int hex(char c); +char *strreplace_chars(char needle, const char *haystack, const char *replace); + +#endif /* PERF_STRING_H */ -- cgit v1.3.1