Author: jhb Date: Tue Dec 8 18:00:58 2020 New Revision: 368455 URL: https://svnweb.freebsd.org/changeset/base/368455
Log: Check that the frame pointer is within the current stack. This same check is used on other architectures. Previously this would permit a stack frame to unwind into any arbitrary kernel address (including unmapped addresses). Reviewed by: andrew, markj Obtained from: CheriBSD Sponsored by: DARPA Differential Revision: https://reviews.freebsd.org/D27362 Modified: head/sys/arm64/arm64/db_trace.c head/sys/arm64/arm64/stack_machdep.c head/sys/arm64/arm64/unwind.c head/sys/arm64/include/csan.h head/sys/arm64/include/stack.h head/sys/cddl/dev/dtrace/aarch64/dtrace_isa.c head/sys/cddl/dev/fbt/fbt.c Modified: head/sys/arm64/arm64/db_trace.c ============================================================================== --- head/sys/arm64/arm64/db_trace.c Tue Dec 8 17:57:18 2020 (r368454) +++ head/sys/arm64/arm64/db_trace.c Tue Dec 8 18:00:58 2020 (r368455) @@ -65,7 +65,7 @@ db_md_set_watchpoint(db_expr_t addr, db_expr_t size) } static void -db_stack_trace_cmd(struct unwind_state *frame) +db_stack_trace_cmd(struct thread *td, struct unwind_state *frame) { c_db_sym_t sym; const char *name; @@ -74,10 +74,8 @@ db_stack_trace_cmd(struct unwind_state *frame) while (1) { uintptr_t pc = frame->pc; - int ret; - ret = unwind_frame(frame); - if (ret < 0) + if (!unwind_frame(td, frame)) break; sym = db_search_symbol(pc, DB_STGY_ANY, &offset); @@ -112,7 +110,7 @@ db_trace_thread(struct thread *thr, int count) frame.sp = (uintptr_t)ctx->pcb_sp; frame.fp = (uintptr_t)ctx->pcb_x[29]; frame.pc = (uintptr_t)ctx->pcb_x[30]; - db_stack_trace_cmd(&frame); + db_stack_trace_cmd(thr, &frame); } else db_trace_self(); return (0); @@ -129,5 +127,5 @@ db_trace_self(void) frame.sp = sp; frame.fp = (uintptr_t)__builtin_frame_address(0); frame.pc = (uintptr_t)db_trace_self; - db_stack_trace_cmd(&frame); + db_stack_trace_cmd(curthread, &frame); } Modified: head/sys/arm64/arm64/stack_machdep.c ============================================================================== --- head/sys/arm64/arm64/stack_machdep.c Tue Dec 8 17:57:18 2020 (r368454) +++ head/sys/arm64/arm64/stack_machdep.c Tue Dec 8 18:00:58 2020 (r368455) @@ -43,15 +43,15 @@ __FBSDID("$FreeBSD$"); #include <machine/stack.h> static void -stack_capture(struct stack *st, struct unwind_state *frame) +stack_capture(struct thread *td, struct stack *st, struct unwind_state *frame) { stack_zero(st); while (1) { - unwind_frame(frame); - if (!INKERNEL((vm_offset_t)frame->fp) || - !INKERNEL((vm_offset_t)frame->pc)) + if (!unwind_frame(td, frame)) break; + if (!INKERNEL((vm_offset_t)frame->pc)) + break; if (stack_put(st, frame->pc) == -1) break; } @@ -73,7 +73,7 @@ stack_save_td(struct stack *st, struct thread *td) frame.fp = td->td_pcb->pcb_x[29]; frame.pc = td->td_pcb->pcb_x[30]; - stack_capture(st, &frame); + stack_capture(td, st, &frame); return (0); } @@ -89,5 +89,5 @@ stack_save(struct stack *st) frame.fp = (uintptr_t)__builtin_frame_address(0); frame.pc = (uintptr_t)stack_save; - stack_capture(st, &frame); + stack_capture(curthread, st, &frame); } Modified: head/sys/arm64/arm64/unwind.c ============================================================================== --- head/sys/arm64/arm64/unwind.c Tue Dec 8 17:57:18 2020 (r368454) +++ head/sys/arm64/arm64/unwind.c Tue Dec 8 18:00:58 2020 (r368455) @@ -30,24 +30,26 @@ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include <sys/param.h> +#include <sys/proc.h> #include <machine/stack.h> #include <machine/vmparam.h> -int -unwind_frame(struct unwind_state *frame) +bool +unwind_frame(struct thread *td, struct unwind_state *frame) { uintptr_t fp; fp = frame->fp; - if (!INKERNEL(fp)) - return (-1); + if (!kstack_contains(td, fp, sizeof(uintptr_t) * 2)) + return (false); + frame->sp = fp + sizeof(uintptr_t) * 2; /* FP to previous frame (X29) */ frame->fp = ((uintptr_t *)fp)[0]; /* LR (X30) */ frame->pc = ((uintptr_t *)fp)[1] - 4; - return (0); + return (true); } Modified: head/sys/arm64/include/csan.h ============================================================================== --- head/sys/arm64/include/csan.h Tue Dec 8 17:57:18 2020 (r368454) +++ head/sys/arm64/include/csan.h Tue Dec 8 18:00:58 2020 (r368455) @@ -87,9 +87,9 @@ kcsan_md_unwind(void) nsym = 0; while (1) { - unwind_frame(&frame); - if (!INKERNEL((vm_offset_t)frame.fp) || - !INKERNEL((vm_offset_t)frame.pc)) + if (!unwind_frame(curthread, &frame)) + break; + if (!INKERNEL((vm_offset_t)frame.pc)) break; #ifdef DDB Modified: head/sys/arm64/include/stack.h ============================================================================== --- head/sys/arm64/include/stack.h Tue Dec 8 17:57:18 2020 (r368454) +++ head/sys/arm64/include/stack.h Tue Dec 8 18:00:58 2020 (r368455) @@ -38,6 +38,6 @@ struct unwind_state { uintptr_t pc; }; -int unwind_frame(struct unwind_state *); +bool unwind_frame(struct thread *, struct unwind_state *); #endif /* !_MACHINE_STACK_H_ */ Modified: head/sys/cddl/dev/dtrace/aarch64/dtrace_isa.c ============================================================================== --- head/sys/cddl/dev/dtrace/aarch64/dtrace_isa.c Tue Dec 8 17:57:18 2020 (r368454) +++ head/sys/cddl/dev/dtrace/aarch64/dtrace_isa.c Tue Dec 8 18:00:58 2020 (r368455) @@ -70,7 +70,7 @@ dtrace_getpcstack(pc_t *pcstack, int pcstack_limit, in { struct unwind_state state; int scp_offset; - register_t sp, fp; + register_t sp; int depth; depth = 0; @@ -88,16 +88,11 @@ dtrace_getpcstack(pc_t *pcstack, int pcstack_limit, in state.pc = (uintptr_t)dtrace_getpcstack; while (depth < pcstack_limit) { - if (!INKERNEL(state.pc) || !INKERNEL(state.fp)) + if (!unwind_frame(curthread, &state)) break; + if (!INKERNEL(state.pc)) + break; - fp = state.fp; - state.sp = fp + 0x10; - /* FP to previous frame (X29) */ - state.fp = *(register_t *)(fp); - /* LR (X30) */ - state.pc = *(register_t *)(fp + 8) - 4; - /* * NB: Unlike some other architectures, we don't need to * explicitly insert cpu_dtrace_caller as it appears in the @@ -274,10 +269,10 @@ dtrace_getstackdepth(int aframes) int scp_offset; register_t sp; int depth; - int done; + bool done; depth = 1; - done = 0; + done = false; __asm __volatile("mov %0, sp" : "=&r" (sp)); @@ -286,7 +281,7 @@ dtrace_getstackdepth(int aframes) state.pc = (uintptr_t)dtrace_getstackdepth; do { - done = unwind_frame(&state); + done = !unwind_frame(curthread, &state); if (!INKERNEL(state.pc) || !INKERNEL(state.fp)) break; depth++; Modified: head/sys/cddl/dev/fbt/fbt.c ============================================================================== --- head/sys/cddl/dev/fbt/fbt.c Tue Dec 8 17:57:18 2020 (r368454) +++ head/sys/cddl/dev/fbt/fbt.c Tue Dec 8 18:00:58 2020 (r368455) @@ -140,7 +140,7 @@ fbt_excluded(const char *name) * Stack unwinders may be called from probe context on some * platforms. */ -#if defined(__riscv) +#if defined(__aarch64__) || defined(__riscv) if (strcmp(name, "unwind_frame") == 0) return (1); 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