[PATCH] unwinder: more sanity checks in Dwarf2 unwinder

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

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>

5 files changed, 35 insertions, 15 deletions

diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 86d8476be4fe..c447807e2a45 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -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;
 }
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 9864d195c408..4fdd162f0bef 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -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;
 }
diff --git a/include/asm-i386/unwind.h b/include/asm-i386/unwind.h
index 601fc67bd775..aa2c931e30db 100644
--- a/include/asm-i386/unwind.h
+++ b/include/asm-i386/unwind.h
@@ -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.eip < __fix_to_virt(FIX_VDSO) + PAGE_SIZE)
                || info->regs.esp < PAGE_OFFSET;
-#endif
 }
 
 #else
diff --git a/include/asm-x86_64/unwind.h b/include/asm-x86_64/unwind.h
index 2e7ff10fd775..2f6349e48717 100644
--- a/include/asm-x86_64/unwind.h
+++ b/include/asm-x86_64/unwind.h
@@ -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
diff --git a/kernel/unwind.c b/kernel/unwind.c
index af48168a3afb..7e721f104105 100644
--- a/kernel/unwind.c
+++ b/kernel/unwind.c
@@ -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