* [PATCH] Fix crash with DW_FORM_implicit_const
@ 2023-07-20 22:11 Tom Tromey
2023-07-21 8:40 ` Andrew Burgess
0 siblings, 1 reply; 2+ messages in thread
From: Tom Tromey @ 2023-07-20 22:11 UTC (permalink / raw)
To: gdb-patches; +Cc: Tom Tromey
Jakub pointed out that using DW_FORM_implicit_const with
DW_AT_bit_size would cause gdb to crash. This happened because
DW_FORM_implicit_const is not an "unsigned" form, causing as_unsigned
to assert. This patch fixes the problem.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30651
---
gdb/dwarf2/read.c | 29 ++++++++++++++++------------
gdb/testsuite/gdb.dwarf2/intbits.exp | 2 +-
gdb/testsuite/lib/dwarf.exp | 4 ++++
3 files changed, 22 insertions(+), 13 deletions(-)
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 3508f2c29ee..b1f1c1d7257 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -15420,20 +15420,25 @@ read_base_type (struct die_info *die, struct dwarf2_cu *cu)
if (TYPE_SPECIFIC_FIELD (type) == TYPE_SPECIFIC_INT)
{
attr = dwarf2_attr (die, DW_AT_bit_size, cu);
- if (attr != nullptr && attr->as_unsigned () <= 8 * type->length ())
+ if (attr != nullptr && attr->form_is_constant ())
{
- unsigned real_bit_size = attr->as_unsigned ();
- attr = dwarf2_attr (die, DW_AT_data_bit_offset, cu);
- /* Only use the attributes if they make sense together. */
- if (attr == nullptr
- || (attr->as_unsigned () + real_bit_size
- <= 8 * type->length ()))
+ unsigned real_bit_size = attr->constant_value (0);
+ if (real_bit_size >= 0 && real_bit_size <= 8 * type->length ())
{
- TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_size
- = real_bit_size;
- if (attr != nullptr)
- TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_offset
- = attr->as_unsigned ();
+ attr = dwarf2_attr (die, DW_AT_data_bit_offset, cu);
+ /* Only use the attributes if they make sense together. */
+ if (attr == nullptr
+ || (attr->form_is_constant ()
+ && attr->constant_value (0) >= 0
+ && (attr->constant_value (0) + real_bit_size
+ <= 8 * type->length ())))
+ {
+ TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_size
+ = real_bit_size;
+ if (attr != nullptr)
+ TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_offset
+ = attr->constant_value (0);
+ }
}
}
}
diff --git a/gdb/testsuite/gdb.dwarf2/intbits.exp b/gdb/testsuite/gdb.dwarf2/intbits.exp
index c52e709316b..cf44d26b721 100644
--- a/gdb/testsuite/gdb.dwarf2/intbits.exp
+++ b/gdb/testsuite/gdb.dwarf2/intbits.exp
@@ -43,7 +43,7 @@ Dwarf::assemble ${asm_file} {
{DW_AT_endianity @DW_END_little}
{DW_AT_name "i7"}
{DW_AT_byte_size 2 DW_FORM_udata}
- {DW_AT_bit_size 7 DW_FORM_udata}
+ {DW_AT_bit_size 7 DW_FORM_implicit_const}
}
DW_TAG_variable {
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index 434495df24a..f09da0430ab 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -693,6 +693,7 @@ namespace eval Dwarf {
_op .ascii [_quote $value]
}
+ DW_FORM_implicit_const -
DW_FORM_flag_present {
# We don't need to emit anything.
}
@@ -917,6 +918,9 @@ namespace eval Dwarf {
}
_op .uleb128 $_constants($attr_name) $attr_name
_op .uleb128 $_constants($attr_form) $attr_form_comment
+ if {$attr_form eq "DW_FORM_implicit_const"} {
+ _op .sleb128 $attr_value "the constant"
+ }
}
}
--
2.41.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] Fix crash with DW_FORM_implicit_const
2023-07-20 22:11 [PATCH] Fix crash with DW_FORM_implicit_const Tom Tromey
@ 2023-07-21 8:40 ` Andrew Burgess
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Burgess @ 2023-07-21 8:40 UTC (permalink / raw)
To: Tom Tromey, gdb-patches; +Cc: Tom Tromey
Tom Tromey <tom@tromey.com> writes:
> Jakub pointed out that using DW_FORM_implicit_const with
> DW_AT_bit_size would cause gdb to crash. This happened because
> DW_FORM_implicit_const is not an "unsigned" form, causing as_unsigned
> to assert. This patch fixes the problem.
LGTM.
Approved-By: Andrew Burgess <aburgess@redhat.com>
Thanks,
Andrew
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30651
> ---
> gdb/dwarf2/read.c | 29 ++++++++++++++++------------
> gdb/testsuite/gdb.dwarf2/intbits.exp | 2 +-
> gdb/testsuite/lib/dwarf.exp | 4 ++++
> 3 files changed, 22 insertions(+), 13 deletions(-)
>
> diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
> index 3508f2c29ee..b1f1c1d7257 100644
> --- a/gdb/dwarf2/read.c
> +++ b/gdb/dwarf2/read.c
> @@ -15420,20 +15420,25 @@ read_base_type (struct die_info *die, struct dwarf2_cu *cu)
> if (TYPE_SPECIFIC_FIELD (type) == TYPE_SPECIFIC_INT)
> {
> attr = dwarf2_attr (die, DW_AT_bit_size, cu);
> - if (attr != nullptr && attr->as_unsigned () <= 8 * type->length ())
> + if (attr != nullptr && attr->form_is_constant ())
> {
> - unsigned real_bit_size = attr->as_unsigned ();
> - attr = dwarf2_attr (die, DW_AT_data_bit_offset, cu);
> - /* Only use the attributes if they make sense together. */
> - if (attr == nullptr
> - || (attr->as_unsigned () + real_bit_size
> - <= 8 * type->length ()))
> + unsigned real_bit_size = attr->constant_value (0);
> + if (real_bit_size >= 0 && real_bit_size <= 8 * type->length ())
> {
> - TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_size
> - = real_bit_size;
> - if (attr != nullptr)
> - TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_offset
> - = attr->as_unsigned ();
> + attr = dwarf2_attr (die, DW_AT_data_bit_offset, cu);
> + /* Only use the attributes if they make sense together. */
> + if (attr == nullptr
> + || (attr->form_is_constant ()
> + && attr->constant_value (0) >= 0
> + && (attr->constant_value (0) + real_bit_size
> + <= 8 * type->length ())))
> + {
> + TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_size
> + = real_bit_size;
> + if (attr != nullptr)
> + TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_offset
> + = attr->constant_value (0);
> + }
> }
> }
> }
> diff --git a/gdb/testsuite/gdb.dwarf2/intbits.exp b/gdb/testsuite/gdb.dwarf2/intbits.exp
> index c52e709316b..cf44d26b721 100644
> --- a/gdb/testsuite/gdb.dwarf2/intbits.exp
> +++ b/gdb/testsuite/gdb.dwarf2/intbits.exp
> @@ -43,7 +43,7 @@ Dwarf::assemble ${asm_file} {
> {DW_AT_endianity @DW_END_little}
> {DW_AT_name "i7"}
> {DW_AT_byte_size 2 DW_FORM_udata}
> - {DW_AT_bit_size 7 DW_FORM_udata}
> + {DW_AT_bit_size 7 DW_FORM_implicit_const}
> }
>
> DW_TAG_variable {
> diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
> index 434495df24a..f09da0430ab 100644
> --- a/gdb/testsuite/lib/dwarf.exp
> +++ b/gdb/testsuite/lib/dwarf.exp
> @@ -693,6 +693,7 @@ namespace eval Dwarf {
> _op .ascii [_quote $value]
> }
>
> + DW_FORM_implicit_const -
> DW_FORM_flag_present {
> # We don't need to emit anything.
> }
> @@ -917,6 +918,9 @@ namespace eval Dwarf {
> }
> _op .uleb128 $_constants($attr_name) $attr_name
> _op .uleb128 $_constants($attr_form) $attr_form_comment
> + if {$attr_form eq "DW_FORM_implicit_const"} {
> + _op .sleb128 $attr_value "the constant"
> + }
> }
> }
>
> --
> 2.41.0
^ permalink raw reply [flat|nested] 2+ messages in thread
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2023-07-21 8:40 ` Andrew Burgess
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