From 0327869232a2f447474306a4d88214324d8abd40 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Sun, 28 May 2017 08:06:54 -0600 Subject: [PATCH] Fix size check in dwarf2_evaluate_loc_desc_full This Rust bug report: https://github.com/rust-lang/rust/issues/41970 noted an error from gdb. What is happening here (for me, the original report had a different error) is that a pieced DWARF expression is not writing to every byte in the resulting value. GDB errors in this case. However, it seems to me that it is always valid to write fewer bytes; the issue comes from writing too many -- that is, the test is reversed. The test was also checking the sub-object, but this also seems incorrect, as it's expected for the expression to write the entirety of the enclosing object. So, this patch reverses the test and applies it to the outer type, not the subobject type. Regtested on the buildbot. gdb/ChangeLog 2017-07-09 Tom Tromey * dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Reverse size check and apply to outer type. gdb/testsuite/ChangeLog 2017-07-09 Tom Tromey * gdb.dwarf2/shortpiece.exp: New file. --- gdb/ChangeLog | 5 ++ gdb/dwarf2loc.c | 4 +- gdb/testsuite/ChangeLog | 4 + gdb/testsuite/gdb.dwarf2/shortpiece.exp | 100 ++++++++++++++++++++++++ 4 files changed, 112 insertions(+), 1 deletion(-) create mode 100644 gdb/testsuite/gdb.dwarf2/shortpiece.exp diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 42fdda6f59..86a41b60ea 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2017-07-09 Tom Tromey + + * dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Reverse size + check and apply to outer type. + 2017-07-07 John Baldwin * fbsd-tdep.c (LWPINFO_OFFSET, LWPINFO_PL_FLAGS) diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c index 8506f3e759..d33c83eda3 100644 --- a/gdb/dwarf2loc.c +++ b/gdb/dwarf2loc.c @@ -2398,7 +2398,9 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame, for (i = 0; i < ctx.num_pieces; ++i) bit_size += ctx.pieces[i].size; - if (8 * (subobj_byte_offset + TYPE_LENGTH (subobj_type)) > bit_size) + /* Complain if the expression is larger than the size of the + outer type. */ + if (bit_size > 8 * TYPE_LENGTH (type)) invalid_synthetic_pointer (); c = allocate_piece_closure (per_cu, ctx.num_pieces, ctx.pieces, diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 8f28f4467d..6b22498783 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2017-07-09 Tom Tromey + + * gdb.dwarf2/shortpiece.exp: New file. + 2017-07-06 David Blaikie * gdb.dwarf2/fission-multi-cu.S: Test containing multiple CUs in a DWO, diff --git a/gdb/testsuite/gdb.dwarf2/shortpiece.exp b/gdb/testsuite/gdb.dwarf2/shortpiece.exp new file mode 100644 index 0000000000..8526a70e7a --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/shortpiece.exp @@ -0,0 +1,100 @@ +# Copyright 2017 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +load_lib dwarf.exp + +# This test can only be run on targets which support DWARF-2 and use gas. +if {![dwarf2_support]} { + return 0 +} + +standard_testfile main.c shortpiece-dw.S + +# Make some DWARF for the test. +set asm_file [standard_output_file $srcfile2] +Dwarf::assemble $asm_file { + global pair + + cu { addr_size 4 } { + compile_unit {} { + declare_labels int_label ushort_label struct_label + + int_label: DW_TAG_base_type { + {DW_AT_byte_size 4 DW_FORM_udata} + {DW_AT_encoding @DW_ATE_unsigned} + {DW_AT_name "myint"} + } + ushort_label: DW_TAG_base_type { + {DW_AT_byte_size 2 DW_FORM_udata} + {DW_AT_encoding @DW_ATE_unsigned} + {DW_AT_name "myushort"} + } + + struct_label: DW_TAG_structure_type { + {DW_AT_name "S"} + {DW_AT_byte_size 8 DW_FORM_udata} + } { + DW_TAG_member { + {DW_AT_name "a"} + {DW_AT_type :${int_label}} + {DW_AT_data_member_location 0 DW_FORM_udata} + } + + DW_TAG_member { + {DW_AT_name "b"} + {DW_AT_type :${ushort_label}} + {DW_AT_data_member_location 4 DW_FORM_udata} + } + } + + DW_TAG_variable { + {DW_AT_name "s1"} + {DW_AT_type :${struct_label}} + {DW_AT_external 1 DW_FORM_flag} + {DW_AT_location { + DW_OP_constu 1 + DW_OP_stack_value + DW_OP_piece 4 + DW_OP_constu 0 + DW_OP_stack_value + DW_OP_piece 2 + } SPECIAL_expr} + } + + DW_TAG_variable { + {DW_AT_name "s2"} + {DW_AT_type :${struct_label}} + {DW_AT_external 1 DW_FORM_flag} + {DW_AT_location { + DW_OP_constu 1 + DW_OP_stack_value + DW_OP_piece 4 + DW_OP_constu 0 + DW_OP_stack_value + DW_OP_piece 8 + } SPECIAL_expr} + } + } + } +} + +if { [prepare_for_testing "failed to prepare" ${testfile} \ + [list $srcfile $asm_file] {nodebug}] } { + return -1 +} + +gdb_test "p s1" " = {a = 1, b = 0}" +gdb_test "p s2" \ + "access outside bounds of object referenced via synthetic pointer"