130 lines
3.7 KiB
Diff
130 lines
3.7 KiB
Diff
commit fa2e3415185a28542d419a641ecd6cddd52e3cd9
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Author: Mark Wielaard <mjw@redhat.com>
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Date: Wed May 11 15:27:48 2011 -0400
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CVE-2011-1781, CVE-2011-1769: correct DW_OP_{mod,div} division-by-zero bug
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Probing a process with corrupted DWARF information, it has been
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possible to create a kernel-side divison-by-zero. This fixes.
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Handle DW_OP_div/mod divide by zero. DW_OP_mod should work unsigned.
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* loc2c.c (translate): Use helper functions div_op and mod_op for
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DW_OP_div and DW_OP_mod operands. Set used_deref = true.
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* translate.cxx (translate_runtime): Emit STAP_MSG_LOC2C_03 define.
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* runtime/loc2c-runtime.h: Define dwarf_div_op and dwarf_mod_op macros.
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* runtime/unwind.c (compute_expr): Check for zero before executing
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DW_OP_mod or DW_OP_div.
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diff --git a/loc2c.c b/loc2c.c
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index 331090c..5f0dd09 100644
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--- a/loc2c.c
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+++ b/loc2c.c
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@@ -681,7 +681,6 @@ translate (struct location_context *ctx, int indent,
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UNOP (abs, op_abs);
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BINOP (and, &);
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BINOP (minus, -);
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- BINOP (mod, %);
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BINOP (mul, *);
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UNOP (neg, -);
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UNOP (not, ~);
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@@ -716,9 +715,21 @@ translate (struct location_context *ctx, int indent,
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{
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POP (b);
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POP (a);
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- push ("(%s) " STACKFMT " / (%s)" STACKFMT,
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+ push ("dwarf_div_op((%s) " STACKFMT ", (%s) " STACKFMT ")",
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stack_slot_type (loc, true), a,
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stack_slot_type (loc, true), b);
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+ used_deref = true;
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+ break;
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+ }
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+
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+ case DW_OP_mod:
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+ {
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+ POP (b);
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+ POP (a);
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+ push ("dwarf_mod_op((%s) " STACKFMT ", (%s) " STACKFMT ")",
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+ stack_slot_type (loc, false), a,
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+ stack_slot_type (loc, false), b);
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+ used_deref = true;
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break;
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}
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diff --git a/runtime/loc2c-runtime.h b/runtime/loc2c-runtime.h
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index d511087..968045f 100644
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--- a/runtime/loc2c-runtime.h
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+++ b/runtime/loc2c-runtime.h
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@@ -82,6 +82,28 @@
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})
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#endif
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+/* dwarf_div_op and dwarf_mod_op do division and modulo operations catching any
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+ divide by zero issues. When they detect div_by_zero they "fault"
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+ by jumping to the (slightly misnamed) deref_fault label. */
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+#define dwarf_div_op(a,b) ({ \
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+ if (b == 0) { \
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+ snprintf(c->error_buffer, sizeof(c->error_buffer), \
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+ "divide by zero in DWARF operand (%s)", "DW_OP_div"); \
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+ c->last_error = c->error_buffer; \
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+ goto deref_fault; \
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+ } \
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+ a / b; \
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+})
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+#define dwarf_mod_op(a,b) ({ \
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+ if (b == 0) { \
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+ snprintf(c->error_buffer, sizeof(c->error_buffer), \
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+ "divide by zero in DWARF operand (%s)", "DW_OP_mod"); \
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+ c->last_error = c->error_buffer; \
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+ goto deref_fault; \
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+ } \
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+ a % b; \
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+})
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+
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/* PR 10601: user-space (user_regset) register access. */
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#if defined(STAPCONF_REGSET)
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#include <linux/regset.h>
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diff --git a/runtime/unwind.c b/runtime/unwind.c
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index 3e56965..810d9eb 100644
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--- a/runtime/unwind.c
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+++ b/runtime/unwind.c
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@@ -856,12 +856,26 @@ static int compute_expr(const u8 *expr, struct unwind_frame_info *frame,
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BINOP(plus, +);
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BINOP(minus, -);
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BINOP(mul, *);
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- BINOP(div, /);
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- BINOP(mod, %);
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BINOP(shl, <<);
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BINOP(shra, >>);
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#undef BINOP
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+ case DW_OP_mod: {
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+ unsigned long b = POP;
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+ unsigned long a = POP;
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+ if (b == 0)
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+ goto divzero;
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+ PUSH (a % b);
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+ }
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+
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+ case DW_OP_div: {
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+ long b = POP;
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+ long a = POP;
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+ if (b == 0)
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+ goto divzero;
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+ PUSH (a / b);
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+ }
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+
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case DW_OP_shr: {
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unsigned long b = POP;
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unsigned long a = POP;
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@@ -944,6 +958,9 @@ overflow:
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underflow:
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_stp_warn("DWARF expression stack underflow in CFI\n");
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return 1;
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+divzero:
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+ _stp_warn("DWARF expression stack divide by zero in CFI\n");
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+ return 1;
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#undef NEED
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#undef PUSH
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