From c8e3dd86600a1a7b165478cc626d69bf07967c15 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 15 Feb 2020 11:28:09 -0500 Subject: [PATCH] x86 user stack frame reads: switch to explicit __get_user() rather than relying upon the magic in raw_copy_from_user() Signed-off-by: Al Viro --- arch/x86/events/core.c | 27 +++++++-------------------- arch/x86/include/asm/uaccess.h | 9 --------- arch/x86/kernel/stacktrace.c | 6 ++++-- 3 files changed, 11 insertions(+), 31 deletions(-) diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 3bb738f5a472..a619763e96e1 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2490,7 +2490,7 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent /* 32-bit process in 64-bit kernel. */ unsigned long ss_base, cs_base; struct stack_frame_ia32 frame; - const void __user *fp; + const struct stack_frame_ia32 __user *fp; if (!test_thread_flag(TIF_IA32)) return 0; @@ -2501,18 +2501,12 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent fp = compat_ptr(ss_base + regs->bp); pagefault_disable(); while (entry->nr < entry->max_stack) { - unsigned long bytes; - frame.next_frame = 0; - frame.return_address = 0; - if (!valid_user_frame(fp, sizeof(frame))) break; - bytes = __copy_from_user_nmi(&frame.next_frame, fp, 4); - if (bytes != 0) + if (__get_user(frame.next_frame, &fp->next_frame)) break; - bytes = __copy_from_user_nmi(&frame.return_address, fp+4, 4); - if (bytes != 0) + if (__get_user(frame.return_address, &fp->return_address)) break; perf_callchain_store(entry, cs_base + frame.return_address); @@ -2533,7 +2527,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { struct stack_frame frame; - const unsigned long __user *fp; + const struct stack_frame __user *fp; if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { /* TODO: We don't support guest os callchain now */ @@ -2546,7 +2540,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs if (regs->flags & (X86_VM_MASK | PERF_EFLAGS_VM)) return; - fp = (unsigned long __user *)regs->bp; + fp = (void __user *)regs->bp; perf_callchain_store(entry, regs->ip); @@ -2558,19 +2552,12 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs pagefault_disable(); while (entry->nr < entry->max_stack) { - unsigned long bytes; - - frame.next_frame = NULL; - frame.return_address = 0; - if (!valid_user_frame(fp, sizeof(frame))) break; - bytes = __copy_from_user_nmi(&frame.next_frame, fp, sizeof(*fp)); - if (bytes != 0) + if (__get_user(frame.next_frame, &fp->next_frame)) break; - bytes = __copy_from_user_nmi(&frame.return_address, fp + 1, sizeof(*fp)); - if (bytes != 0) + if (__get_user(frame.return_address, &fp->return_address)) break; perf_callchain_store(entry, frame.return_address); diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 61d93f062a36..ab8eab43a8a2 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -694,15 +694,6 @@ extern struct movsl_mask { # include #endif -/* - * We rely on the nested NMI work to allow atomic faults from the NMI path; the - * nested NMI paths are careful to preserve CR2. - * - * Caller must use pagefault_enable/disable, or run in interrupt context, - * and also do a uaccess_ok() check - */ -#define __copy_from_user_nmi __copy_from_user_inatomic - /* * The "unsafe" user accesses aren't really "unsafe", but the naming * is a big fat warning: you have to not only do the access_ok() diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 2d6898c2cb64..6ad43fc44556 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -96,7 +96,8 @@ struct stack_frame_user { }; static int -copy_stack_frame(const void __user *fp, struct stack_frame_user *frame) +copy_stack_frame(const struct stack_frame_user __user *fp, + struct stack_frame_user *frame) { int ret; @@ -105,7 +106,8 @@ copy_stack_frame(const void __user *fp, struct stack_frame_user *frame) ret = 1; pagefault_disable(); - if (__copy_from_user_inatomic(frame, fp, sizeof(*frame))) + if (__get_user(frame->next_fp, &fp->next_fp) || + __get_user(frame->ret_addr, &fp->ret_addr)) ret = 0; pagefault_enable();