Commit 359ad0d4 authored by Jan Beulich's avatar Jan Beulich Committed by Andi Kleen
Browse files

[PATCH] unwinder: more sanity checks in Dwarf2 unwinder 



Tighten the requirements on both input to and output from the Dwarf2
unwinder.

Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent eef5e0d1

arch/i386/kernel/traps.c

+7 −0
Original line number Diff line number Diff line
@@ -161,12 +161,19 @@ dump_trace_unwind(struct unwind_frame_info *info, void *data) 
{

	struct ops_and_data *oad = (struct ops_and_data *)data;

	int n = 0;

	unsigned long sp = UNW_SP(info);



	if (arch_unw_user_mode(info))

		return -1;

	while (unwind(info) == 0 && UNW_PC(info)) {

		n++;

		oad->ops->address(oad->data, UNW_PC(info));

		if (arch_unw_user_mode(info))

			break;

		if ((sp & ~(PAGE_SIZE - 1)) == (UNW_SP(info) & ~(PAGE_SIZE - 1))

		    && sp > UNW_SP(info))

			break;

		sp = UNW_SP(info);

	}

	return n;

}

arch/x86_64/kernel/traps.c

+7 −0
Original line number Diff line number Diff line
@@ -225,12 +225,19 @@ static int dump_trace_unwind(struct unwind_frame_info *info, void *context) 
{

	struct ops_and_data *oad = (struct ops_and_data *)context;

	int n = 0;

	unsigned long sp = UNW_SP(info);



	if (arch_unw_user_mode(info))

		return -1;

	while (unwind(info) == 0 && UNW_PC(info)) {

		n++;

		oad->ops->address(oad->data, UNW_PC(info));

		if (arch_unw_user_mode(info))

			break;

		if ((sp & ~(PAGE_SIZE - 1)) == (UNW_SP(info) & ~(PAGE_SIZE - 1))

		    && sp > UNW_SP(info))

			break;

		sp = UNW_SP(info);

	}

	return n;

}

include/asm-i386/unwind.h

+4 −8
Original line number Diff line number Diff line
@@ -79,17 +79,13 @@ extern asmlinkage int arch_unwind_init_running(struct unwind_frame_info *, 
                                                                          void *arg),

                                               void *arg);



static inline int arch_unw_user_mode(const struct unwind_frame_info *info)

static inline int arch_unw_user_mode(/*const*/ struct unwind_frame_info *info)

{

#if 0 /* This can only work when selector register and EFLAGS saves/restores

         are properly annotated (and tracked in UNW_REGISTER_INFO). */

	return user_mode_vm(&info->regs);

#else

	return info->regs.eip < PAGE_OFFSET

	return user_mode_vm(&info->regs)

	       || info->regs.eip < PAGE_OFFSET

	       || (info->regs.eip >= __fix_to_virt(FIX_VDSO)

	           && info->regs.eip < __fix_to_virt(FIX_VDSO) + PAGE_SIZE)

	       || info->regs.esp < PAGE_OFFSET;

#endif

}



#else

include/asm-x86_64/unwind.h

+2 −6
Original line number Diff line number Diff line
@@ -87,14 +87,10 @@ extern int arch_unwind_init_running(struct unwind_frame_info *, 


static inline int arch_unw_user_mode(const struct unwind_frame_info *info)

{

#if 0 /* This can only work when selector register saves/restores

         are properly annotated (and tracked in UNW_REGISTER_INFO). */

	return user_mode(&info->regs);

#else

	return (long)info->regs.rip >= 0

	return user_mode(&info->regs)

	       || (long)info->regs.rip >= 0

	       || (info->regs.rip >= VSYSCALL_START && info->regs.rip < VSYSCALL_END)

	       || (long)info->regs.rsp >= 0;

#endif

}



#else

kernel/unwind.c

+15 −1
Original line number Diff line number Diff line
@@ -95,6 +95,7 @@ static const struct { 


typedef unsigned long uleb128_t;

typedef   signed long sleb128_t;

#define sleb128abs __builtin_labs



static struct unwind_table {

	struct {
@@ -787,7 +788,7 @@ int unwind(struct unwind_frame_info *frame) 
#define FRAME_REG(r, t) (((t *)frame)[reg_info[r].offs])

	const u32 *fde = NULL, *cie = NULL;

	const u8 *ptr = NULL, *end = NULL;

	unsigned long pc = UNW_PC(frame) - frame->call_frame;

	unsigned long pc = UNW_PC(frame) - frame->call_frame, sp;

	unsigned long startLoc = 0, endLoc = 0, cfa;

	unsigned i;

	signed ptrType = -1;
@@ -936,6 +937,9 @@ int unwind(struct unwind_frame_info *frame) 
		state.dataAlign = get_sleb128(&ptr, end);

		if (state.codeAlign == 0 || state.dataAlign == 0 || ptr >= end)

			cie = NULL;

		else if (UNW_PC(frame) % state.codeAlign

		         || UNW_SP(frame) % sleb128abs(state.dataAlign))

			return -EPERM;

		else {

			retAddrReg = state.version <= 1 ? *ptr++ : get_uleb128(&ptr, end);

			/* skip augmentation */
@@ -968,6 +972,8 @@ int unwind(struct unwind_frame_info *frame) 
#ifdef CONFIG_FRAME_POINTER

		unsigned long top, bottom;



		if ((UNW_SP(frame) | UNW_FP(frame)) % sizeof(unsigned long))

			return -EPERM;

		top = STACK_TOP(frame->task);

		bottom = STACK_BOTTOM(frame->task);

# if FRAME_RETADDR_OFFSET < 0
@@ -1018,6 +1024,7 @@ int unwind(struct unwind_frame_info *frame) 
	   || state.regs[retAddrReg].where == Nowhere

	   || state.cfa.reg >= ARRAY_SIZE(reg_info)

	   || reg_info[state.cfa.reg].width != sizeof(unsigned long)

	   || FRAME_REG(state.cfa.reg, unsigned long) % sizeof(unsigned long)

	   || state.cfa.offs % sizeof(unsigned long))

		return -EIO;

	/* update frame */
@@ -1038,6 +1045,8 @@ int unwind(struct unwind_frame_info *frame) 
#else

# define CASES CASE(8); CASE(16); CASE(32); CASE(64)

#endif

	pc = UNW_PC(frame);

	sp = UNW_SP(frame);

	for (i = 0; i < ARRAY_SIZE(state.regs); ++i) {

		if (REG_INVALID(i)) {

			if (state.regs[i].where == Nowhere)
@@ -1118,6 +1127,11 @@ int unwind(struct unwind_frame_info *frame) 
		}

	}



	if (UNW_PC(frame) % state.codeAlign

	    || UNW_SP(frame) % sleb128abs(state.dataAlign)

	    || (pc == UNW_PC(frame) && sp == UNW_SP(frame)))

		return -EIO;



	return 0;

#undef CASES

#undef FRAME_REG