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[patch] 2/3: Fix crash on self-looping DW_OP_fbreg
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Mon, 28 Apr 2008 10:37:32 +0200
- Subject: [patch] 2/3: Fix crash on self-looping DW_OP_fbreg
Hi,
I saw there GDB will naively loop and crash on DW_OP_fbreg contained in the
location list of DW_AT_frame_base.
I am not aware of an existing case using such broken debug info.
dwarf_expr_context->recursion_depth and dwarf_expr_context->max_recursion_depth
are declared but never used in the GDB sources. IMO MAX_RECURSION_DEPTH could
be a constant but I left the code according to the existing declaration.
No regressions on x86_64.
Regards,
Jan
2008-04-28 Jan Kratochvil <jan.kratochvil@redhat.com>
* Makefile.in: Update dependencies.
* dwarf2expr.c: New include "gdb_assert.h".
(new_dwarf_expr_context): Initialize MAX_RECURSION_DEPTH.
(struct dwarf_expr_eval_cleanup, dwarf_expr_eval_cleanup): New.
(dwarf_expr_eval): Protect the RECURSION_DEPTH count for exceptions.
(execute_stack_op): Error out on too large RECURSION_DEPTH.
Increase/decrease RECURSION_DEPTH around the function.
--- ./gdb/Makefile.in 24 Apr 2008 10:21:44 -0000 1.1004
+++ ./gdb/Makefile.in 28 Apr 2008 00:26:38 -0000
@@ -2077,7 +2077,7 @@ dummy-frame.o: dummy-frame.c $(defs_h) $
dfp.o: dfp.c $(defs_h) $(expression_h) $(gdbtypes_h) $(value_h) $(dfp_h) \
$(decimal128_h) $(decimal64_h) $(decimal32_h)
dwarf2expr.o: dwarf2expr.c $(defs_h) $(symtab_h) $(gdbtypes_h) $(value_h) \
- $(gdbcore_h) $(elf_dwarf2_h) $(dwarf2expr_h)
+ $(gdbcore_h) $(elf_dwarf2_h) $(dwarf2expr_h) $(gdb_assert_h)
dwarf2-frame.o: dwarf2-frame.c $(defs_h) $(dwarf2expr_h) $(elf_dwarf2_h) \
$(frame_h) $(frame_base_h) $(frame_unwind_h) $(gdbcore_h) \
$(gdbtypes_h) $(symtab_h) $(objfiles_h) $(regcache_h) \
--- ./gdb/dwarf2expr.c 18 Mar 2008 19:40:47 -0000 1.25
+++ ./gdb/dwarf2expr.c 28 Apr 2008 00:26:50 -0000
@@ -27,6 +27,7 @@
#include "gdbcore.h"
#include "elf/dwarf2.h"
#include "dwarf2expr.h"
+#include "gdb_assert.h"
/* Local prototypes. */
@@ -46,6 +47,7 @@ new_dwarf_expr_context (void)
retval->stack = xmalloc (retval->stack_allocated * sizeof (CORE_ADDR));
retval->num_pieces = 0;
retval->pieces = 0;
+ retval->max_recursion_depth = 0x100;
return retval;
}
@@ -131,10 +133,35 @@ add_piece (struct dwarf_expr_context *ct
/* Evaluate the expression at ADDR (LEN bytes long) using the context
CTX. */
+struct dwarf_expr_eval_cleanup
+ {
+ struct dwarf_expr_context *ctx;
+ int old_recursion_depth;
+ };
+
+static void
+dwarf_expr_eval_cleanup (void *data_voidp)
+{
+ struct dwarf_expr_eval_cleanup *data = data_voidp;
+
+ data->ctx->recursion_depth = data->old_recursion_depth;
+}
+
void
dwarf_expr_eval (struct dwarf_expr_context *ctx, gdb_byte *addr, size_t len)
{
+ struct cleanup *back_to;
+ struct dwarf_expr_eval_cleanup data;
+
+ data.ctx = ctx;
+ data.old_recursion_depth = ctx->recursion_depth;
+ back_to = make_cleanup (dwarf_expr_eval_cleanup, &data);
+
execute_stack_op (ctx, addr, addr + len);
+
+ gdb_assert (ctx->recursion_depth == data.old_recursion_depth);
+ /* It would be a NOP. */
+ discard_cleanups (back_to);
}
/* Decode the unsigned LEB128 constant at BUF into the variable pointed to
@@ -281,6 +308,11 @@ execute_stack_op (struct dwarf_expr_cont
ctx->in_reg = 0;
ctx->initialized = 1; /* Default is initialized. */
+ if (ctx->recursion_depth > ctx->max_recursion_depth)
+ error (_("DWARF-2 expression error: Loop detected (%d)."),
+ ctx->recursion_depth);
+ ctx->recursion_depth++;
+
while (op_ptr < op_end)
{
enum dwarf_location_atom op = *op_ptr++;
@@ -739,4 +771,7 @@ execute_stack_op (struct dwarf_expr_cont
dwarf_expr_push (ctx, result);
no_push:;
}
+
+ ctx->recursion_depth--;
+ gdb_assert (ctx->recursion_depth >= 0);
}