* [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form
@ 2023-01-20 5:08 Simon Marchi
2023-01-20 5:08 ` [PATCH 2/2] gdb/dwarf: fix UBsan crash in read_subrange_type Simon Marchi
2023-01-20 12:51 ` [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form Andrew Burgess
0 siblings, 2 replies; 6+ messages in thread
From: Simon Marchi @ 2023-01-20 5:08 UTC (permalink / raw)
To: gdb-patches; +Cc: Simon Marchi
I am looking at this code [1]:
/* Normally, the DWARF producers are expected to use a signed
constant form (Eg. DW_FORM_sdata) to express negative bounds.
But this is unfortunately not always the case, as witnessed
with GCC, for instance, where the ambiguous DW_FORM_dataN form
is used instead. To work around that ambiguity, we treat
the bounds as signed, and thus sign-extend their values, when
the base type is signed. */
negative_mask =
-((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
if (low.kind () == PROP_CONST
&& !base_type->is_unsigned () && (low.const_val () & negative_mask))
low.set_const_val (low.const_val () | negative_mask);
if (high.kind () == PROP_CONST
&& !base_type->is_unsigned () && (high.const_val () & negative_mask))
high.set_const_val (high.const_val () | negative_mask);
Nothing in the testsuite seems to exercise it, as when I remove it, all
of gdb.dwarf2 still passes. And tests in other directories would be
compiler-dependent, so would rely on having a buggy compiler.
Update gdb.dwarf2/subrange.exp to have a test for it. When removing the
code above, the new test fails with:
ptype array_with_buggy_negative_bounds_type^M
type = array [240..244] of signed_byte^M
(gdb) FAIL: gdb.dwarf2/subrange.exp: ptype array_with_buggy_negative_bounds_type
instead of the expected:
ptype array_with_buggy_negative_bounds_type^M
type = array [-16..-12] of signed_byte^M
(gdb) PASS: gdb.dwarf2/subrange.exp: ptype array_with_buggy_negative_bounds_type
[1] https://gitlab.com/gnutools/binutils-gdb/-/blob/5ea14aa4e53fa37f4ba4517497ed2c1e4c60dee2/gdb/dwarf2/read.c#L17681-17695
Change-Id: I1992a3ff0cb1e90fa8a9114dae6c591792f059c2
---
gdb/testsuite/gdb.dwarf2/subrange.exp | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/gdb/testsuite/gdb.dwarf2/subrange.exp b/gdb/testsuite/gdb.dwarf2/subrange.exp
index 72d7babc88e..8a8443f31a8 100644
--- a/gdb/testsuite/gdb.dwarf2/subrange.exp
+++ b/gdb/testsuite/gdb.dwarf2/subrange.exp
@@ -28,6 +28,7 @@ Dwarf::assemble $asm_file {
compile_unit {{language @DW_LANG_Pascal83}} {
declare_labels byte_label typedef_label array_label
+ # A subrange's underlying type that is a typedef.
byte_label: base_type {
{name byte}
{encoding @DW_ATE_unsigned}
@@ -54,6 +55,28 @@ Dwarf::assemble $asm_file {
{name TByteArray}
{type :$array_label}
}
+
+ # This subrange's underlying type is signed, but the bounds are
+ # specified using a non-signed form.
+ declare_labels signed_byte_label subrange_with_buggy_negative_bounds_label
+
+ signed_byte_label: base_type {
+ {name signed_byte}
+ {encoding @DW_ATE_signed}
+ {byte_size 1 DW_FORM_sdata}
+ }
+
+ # The bounds mean -16 to -12.
+ subrange_with_buggy_negative_bounds_label: subrange_type {
+ {lower_bound 0xf0 DW_FORM_udata}
+ {upper_bound 0xf4 DW_FORM_udata}
+ {type :$signed_byte_label}
+ }
+
+ DW_TAG_variable {
+ {name subrange_with_buggy_negative_bounds_variable}
+ {type :$subrange_with_buggy_negative_bounds_label}
+ }
}
}
}
@@ -67,3 +90,5 @@ gdb_test_no_output "set language pascal"
gdb_test "ptype TByteArray" \
"type = array \\\[0\\.\\.191\\\] of byte"
+gdb_test "ptype subrange_with_buggy_negative_bounds_variable" \
+ "type = -16..-12"
--
2.39.1
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 2/2] gdb/dwarf: fix UBsan crash in read_subrange_type
2023-01-20 5:08 [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form Simon Marchi
@ 2023-01-20 5:08 ` Simon Marchi
2023-01-20 13:03 ` Andrew Burgess
2023-01-20 12:51 ` [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form Andrew Burgess
1 sibling, 1 reply; 6+ messages in thread
From: Simon Marchi @ 2023-01-20 5:08 UTC (permalink / raw)
To: gdb-patches; +Cc: Simon Marchi
When running gdb.ada/arrayptr.exp (and others) on Ubuntu 22.04, with the
`gnat-11` package installed (not `gnat`), with UBSan activated, I get:
(gdb) break foo.adb:40
/home/smarchi/src/binutils-gdb/gdb/dwarf2/read.c:17689:20: runtime error: shift exponent 127 is too large for 64-bit type 'long unsigned int'
The problematic DIEs are:
0x00001460: DW_TAG_subrange_type
DW_AT_lower_bound [DW_FORM_data1] (0x00)
DW_AT_upper_bound [DW_FORM_data16] (ffffffffffffffff3f00000000000000)
DW_AT_name [DW_FORM_strp] ("foo__packed_array___XP7___XDLU_0__1180591620717411303423")
DW_AT_type [DW_FORM_ref4] (0x0000153f "long_long_long_unsigned")
DW_AT_GNAT_descriptive_type [DW_FORM_ref4] (0x0000147e)
DW_AT_artificial [DW_FORM_flag_present] (true)
0x0000153f: DW_TAG_base_type
DW_AT_byte_size [DW_FORM_data1] (0x10)
DW_AT_encoding [DW_FORM_data1] (DW_ATE_unsigned)
DW_AT_name [DW_FORM_strp] ("long_long_long_unsigned")
DW_AT_artificial [DW_FORM_flag_present] (true)
When processed by this code:
negative_mask =
-((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
if (low.kind () == PROP_CONST
&& !base_type->is_unsigned () && (low.const_val () & negative_mask))
low.set_const_val (low.const_val () | negative_mask);
When the base type's length (16 bytes in this case) is larger than a
ULONGEST (typically 8 bytes), the bit shift is too large.
My obvious fix is just to skip the fixup for base types larger than a
ULONGEST (8 bytes). I don't think we really handle constant attribute
values larger than 8 bytes anyway, so this is part of a much larger
problem.
Add a test that replicates this situation, but uses bounds that fit in a
signed 64 bit, so we get a sensible result.
Change-Id: I8d0a24f3edd83b44e0761a0ce38922d3e2e112fb
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29386
---
gdb/dwarf2/read.c | 29 ++++++++++++++++++---------
gdb/testsuite/gdb.dwarf2/subrange.exp | 22 ++++++++++++++++++++
2 files changed, 41 insertions(+), 10 deletions(-)
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 44b54f77de9..87846788604 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -17588,7 +17588,6 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
int low_default_is_valid;
int high_bound_is_count = 0;
const char *name;
- ULONGEST negative_mask;
orig_base_type = read_subrange_index_type (die, cu);
@@ -17684,15 +17683,25 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
with GCC, for instance, where the ambiguous DW_FORM_dataN form
is used instead. To work around that ambiguity, we treat
the bounds as signed, and thus sign-extend their values, when
- the base type is signed. */
- negative_mask =
- -((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
- if (low.kind () == PROP_CONST
- && !base_type->is_unsigned () && (low.const_val () & negative_mask))
- low.set_const_val (low.const_val () | negative_mask);
- if (high.kind () == PROP_CONST
- && !base_type->is_unsigned () && (high.const_val () & negative_mask))
- high.set_const_val (high.const_val () | negative_mask);
+ the base type is signed.
+
+ Skip it if the base type's length is largest than ULONGEST, to avoid
+ the undefined behavior of a too large left shift. We don't really handle
+ constants larger than 8 bytes anyway, at the moment. */
+
+ if (base_type->length () <= sizeof (ULONGEST))
+ {
+ ULONGEST negative_mask
+ = -((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
+
+ if (low.kind () == PROP_CONST
+ && !base_type->is_unsigned () && (low.const_val () & negative_mask))
+ low.set_const_val (low.const_val () | negative_mask);
+
+ if (high.kind () == PROP_CONST
+ && !base_type->is_unsigned () && (high.const_val () & negative_mask))
+ high.set_const_val (high.const_val () | negative_mask);
+ }
/* Check for bit and byte strides. */
struct dynamic_prop byte_stride_prop;
diff --git a/gdb/testsuite/gdb.dwarf2/subrange.exp b/gdb/testsuite/gdb.dwarf2/subrange.exp
index 8a8443f31a8..556422629a3 100644
--- a/gdb/testsuite/gdb.dwarf2/subrange.exp
+++ b/gdb/testsuite/gdb.dwarf2/subrange.exp
@@ -77,6 +77,26 @@ Dwarf::assemble $asm_file {
{name subrange_with_buggy_negative_bounds_variable}
{type :$subrange_with_buggy_negative_bounds_label}
}
+
+ # This subrange's base type is 16-bytes long (although the bounds fit in
+ # signed 64-bit). This is to test the fix for PR 29386.
+ declare_labels a_16_byte_integer_label a_16_byte_subrange_label
+
+ a_16_byte_integer_label: base_type {
+ {byte_size 16 udata}
+ {encoding @DW_ATE_signed}
+ }
+
+ a_16_byte_subrange_label: subrange_type {
+ {lower_bound -9223372036854775808 DW_FORM_sdata}
+ {upper_bound 9223372036854775807 DW_FORM_sdata}
+ {type :$a_16_byte_integer_label}
+ }
+
+ DW_TAG_variable {
+ {name a_16_byte_subrange_variable}
+ {type :$a_16_byte_subrange_label}
+ }
}
}
}
@@ -92,3 +112,5 @@ gdb_test "ptype TByteArray" \
"type = array \\\[0\\.\\.191\\\] of byte"
gdb_test "ptype subrange_with_buggy_negative_bounds_variable" \
"type = -16..-12"
+gdb_test "ptype a_16_byte_subrange_variable" \
+ "type = -9223372036854775808..9223372036854775807"
--
2.39.1
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form
2023-01-20 5:08 [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form Simon Marchi
2023-01-20 5:08 ` [PATCH 2/2] gdb/dwarf: fix UBsan crash in read_subrange_type Simon Marchi
@ 2023-01-20 12:51 ` Andrew Burgess
2023-01-20 16:38 ` Simon Marchi
1 sibling, 1 reply; 6+ messages in thread
From: Andrew Burgess @ 2023-01-20 12:51 UTC (permalink / raw)
To: Simon Marchi via Gdb-patches, gdb-patches; +Cc: Simon Marchi
Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
> I am looking at this code [1]:
>
> /* Normally, the DWARF producers are expected to use a signed
> constant form (Eg. DW_FORM_sdata) to express negative bounds.
> But this is unfortunately not always the case, as witnessed
> with GCC, for instance, where the ambiguous DW_FORM_dataN form
> is used instead. To work around that ambiguity, we treat
> the bounds as signed, and thus sign-extend their values, when
> the base type is signed. */
> negative_mask =
> -((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
> if (low.kind () == PROP_CONST
> && !base_type->is_unsigned () && (low.const_val () & negative_mask))
> low.set_const_val (low.const_val () | negative_mask);
> if (high.kind () == PROP_CONST
> && !base_type->is_unsigned () && (high.const_val () & negative_mask))
> high.set_const_val (high.const_val () | negative_mask);
>
> Nothing in the testsuite seems to exercise it, as when I remove it, all
> of gdb.dwarf2 still passes. And tests in other directories would be
> compiler-dependent, so would rely on having a buggy compiler.
>
> Update gdb.dwarf2/subrange.exp to have a test for it. When removing the
> code above, the new test fails with:
>
> ptype array_with_buggy_negative_bounds_type^M
> type = array [240..244] of signed_byte^M
> (gdb) FAIL: gdb.dwarf2/subrange.exp: ptype array_with_buggy_negative_bounds_type
>
> instead of the expected:
>
> ptype array_with_buggy_negative_bounds_type^M
> type = array [-16..-12] of signed_byte^M
> (gdb) PASS: gdb.dwarf2/subrange.exp: ptype array_with_buggy_negative_bounds_type
>
> [1] https://gitlab.com/gnutools/binutils-gdb/-/blob/5ea14aa4e53fa37f4ba4517497ed2c1e4c60dee2/gdb/dwarf2/read.c#L17681-17695
>
> Change-Id: I1992a3ff0cb1e90fa8a9114dae6c591792f059c2
> ---
> gdb/testsuite/gdb.dwarf2/subrange.exp | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/gdb/testsuite/gdb.dwarf2/subrange.exp b/gdb/testsuite/gdb.dwarf2/subrange.exp
> index 72d7babc88e..8a8443f31a8 100644
> --- a/gdb/testsuite/gdb.dwarf2/subrange.exp
> +++ b/gdb/testsuite/gdb.dwarf2/subrange.exp
> @@ -28,6 +28,7 @@ Dwarf::assemble $asm_file {
> compile_unit {{language @DW_LANG_Pascal83}} {
> declare_labels byte_label typedef_label array_label
>
> + # A subrange's underlying type that is a typedef.
> byte_label: base_type {
> {name byte}
> {encoding @DW_ATE_unsigned}
> @@ -54,6 +55,28 @@ Dwarf::assemble $asm_file {
> {name TByteArray}
> {type :$array_label}
> }
> +
> + # This subrange's underlying type is signed, but the bounds are
> + # specified using a non-signed form.
> + declare_labels signed_byte_label subrange_with_buggy_negative_bounds_label
> +
> + signed_byte_label: base_type {
> + {name signed_byte}
> + {encoding @DW_ATE_signed}
> + {byte_size 1 DW_FORM_sdata}
> + }
> +
> + # The bounds mean -16 to -12.
> + subrange_with_buggy_negative_bounds_label: subrange_type {
> + {lower_bound 0xf0 DW_FORM_udata}
> + {upper_bound 0xf4 DW_FORM_udata}
> + {type :$signed_byte_label}
> + }
> +
> + DW_TAG_variable {
> + {name subrange_with_buggy_negative_bounds_variable}
> + {type :$subrange_with_buggy_negative_bounds_label}
> + }
> }
> }
> }
> @@ -67,3 +90,5 @@ gdb_test_no_output "set language pascal"
>
> gdb_test "ptype TByteArray" \
> "type = array \\\[0\\.\\.191\\\] of byte"
> +gdb_test "ptype subrange_with_buggy_negative_bounds_variable" \
> + "type = -16..-12"
Should be "type = -16\\.\\.-12"
Otherwise, looks good.
Thanks,
Andrew
> --
> 2.39.1
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] gdb/dwarf: fix UBsan crash in read_subrange_type
2023-01-20 5:08 ` [PATCH 2/2] gdb/dwarf: fix UBsan crash in read_subrange_type Simon Marchi
@ 2023-01-20 13:03 ` Andrew Burgess
2023-01-20 16:51 ` Simon Marchi
0 siblings, 1 reply; 6+ messages in thread
From: Andrew Burgess @ 2023-01-20 13:03 UTC (permalink / raw)
To: Simon Marchi via Gdb-patches, gdb-patches; +Cc: Simon Marchi
Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
> When running gdb.ada/arrayptr.exp (and others) on Ubuntu 22.04, with the
> `gnat-11` package installed (not `gnat`), with UBSan activated, I get:
>
> (gdb) break foo.adb:40
> /home/smarchi/src/binutils-gdb/gdb/dwarf2/read.c:17689:20: runtime error: shift exponent 127 is too large for 64-bit type 'long unsigned int'
>
> The problematic DIEs are:
>
> 0x00001460: DW_TAG_subrange_type
> DW_AT_lower_bound [DW_FORM_data1] (0x00)
> DW_AT_upper_bound [DW_FORM_data16] (ffffffffffffffff3f00000000000000)
> DW_AT_name [DW_FORM_strp] ("foo__packed_array___XP7___XDLU_0__1180591620717411303423")
> DW_AT_type [DW_FORM_ref4] (0x0000153f "long_long_long_unsigned")
> DW_AT_GNAT_descriptive_type [DW_FORM_ref4] (0x0000147e)
> DW_AT_artificial [DW_FORM_flag_present] (true)
>
> 0x0000153f: DW_TAG_base_type
> DW_AT_byte_size [DW_FORM_data1] (0x10)
> DW_AT_encoding [DW_FORM_data1] (DW_ATE_unsigned)
> DW_AT_name [DW_FORM_strp] ("long_long_long_unsigned")
> DW_AT_artificial [DW_FORM_flag_present] (true)
>
> When processed by this code:
>
> negative_mask =
> -((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
> if (low.kind () == PROP_CONST
> && !base_type->is_unsigned () && (low.const_val () & negative_mask))
> low.set_const_val (low.const_val () | negative_mask);
>
> When the base type's length (16 bytes in this case) is larger than a
> ULONGEST (typically 8 bytes), the bit shift is too large.
>
> My obvious fix is just to skip the fixup for base types larger than a
> ULONGEST (8 bytes). I don't think we really handle constant attribute
> values larger than 8 bytes anyway, so this is part of a much larger
> problem.
>
> Add a test that replicates this situation, but uses bounds that fit in a
> signed 64 bit, so we get a sensible result.
>
> Change-Id: I8d0a24f3edd83b44e0761a0ce38922d3e2e112fb
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29386
> ---
> gdb/dwarf2/read.c | 29 ++++++++++++++++++---------
> gdb/testsuite/gdb.dwarf2/subrange.exp | 22 ++++++++++++++++++++
> 2 files changed, 41 insertions(+), 10 deletions(-)
>
> diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
> index 44b54f77de9..87846788604 100644
> --- a/gdb/dwarf2/read.c
> +++ b/gdb/dwarf2/read.c
> @@ -17588,7 +17588,6 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
> int low_default_is_valid;
> int high_bound_is_count = 0;
> const char *name;
> - ULONGEST negative_mask;
>
> orig_base_type = read_subrange_index_type (die, cu);
>
> @@ -17684,15 +17683,25 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
> with GCC, for instance, where the ambiguous DW_FORM_dataN form
> is used instead. To work around that ambiguity, we treat
> the bounds as signed, and thus sign-extend their values, when
> - the base type is signed. */
> - negative_mask =
> - -((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
> - if (low.kind () == PROP_CONST
> - && !base_type->is_unsigned () && (low.const_val () & negative_mask))
> - low.set_const_val (low.const_val () | negative_mask);
> - if (high.kind () == PROP_CONST
> - && !base_type->is_unsigned () && (high.const_val () & negative_mask))
> - high.set_const_val (high.const_val () | negative_mask);
> + the base type is signed.
> +
> + Skip it if the base type's length is largest than ULONGEST, to avoid
s/largest/larger/
> + the undefined behavior of a too large left shift. We don't really handle
> + constants larger than 8 bytes anyway, at the moment. */
> +
> + if (base_type->length () <= sizeof (ULONGEST))
> + {
> + ULONGEST negative_mask
> + = -((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
> +
> + if (low.kind () == PROP_CONST
> + && !base_type->is_unsigned () && (low.const_val () & negative_mask))
> + low.set_const_val (low.const_val () | negative_mask);
> +
> + if (high.kind () == PROP_CONST
> + && !base_type->is_unsigned () && (high.const_val () & negative_mask))
> + high.set_const_val (high.const_val () | negative_mask);
> + }
>
> /* Check for bit and byte strides. */
> struct dynamic_prop byte_stride_prop;
> diff --git a/gdb/testsuite/gdb.dwarf2/subrange.exp b/gdb/testsuite/gdb.dwarf2/subrange.exp
> index 8a8443f31a8..556422629a3 100644
> --- a/gdb/testsuite/gdb.dwarf2/subrange.exp
> +++ b/gdb/testsuite/gdb.dwarf2/subrange.exp
> @@ -77,6 +77,26 @@ Dwarf::assemble $asm_file {
> {name subrange_with_buggy_negative_bounds_variable}
> {type :$subrange_with_buggy_negative_bounds_label}
> }
> +
> + # This subrange's base type is 16-bytes long (although the bounds fit in
> + # signed 64-bit). This is to test the fix for PR 29386.
> + declare_labels a_16_byte_integer_label a_16_byte_subrange_label
> +
> + a_16_byte_integer_label: base_type {
> + {byte_size 16 udata}
> + {encoding @DW_ATE_signed}
> + }
> +
> + a_16_byte_subrange_label: subrange_type {
> + {lower_bound -9223372036854775808 DW_FORM_sdata}
> + {upper_bound 9223372036854775807 DW_FORM_sdata}
> + {type :$a_16_byte_integer_label}
> + }
> +
> + DW_TAG_variable {
> + {name a_16_byte_subrange_variable}
> + {type :$a_16_byte_subrange_label}
> + }
> }
> }
> }
> @@ -92,3 +112,5 @@ gdb_test "ptype TByteArray" \
> "type = array \\\[0\\.\\.191\\\] of byte"
> gdb_test "ptype subrange_with_buggy_negative_bounds_variable" \
> "type = -16..-12"
> +gdb_test "ptype a_16_byte_subrange_variable" \
> + "type = -9223372036854775808..9223372036854775807"
As before, I'd use "\\.\\." here.
Looks good with those nits fixed.
Thanks,
Andrew
> --
> 2.39.1
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form
2023-01-20 12:51 ` [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form Andrew Burgess
@ 2023-01-20 16:38 ` Simon Marchi
0 siblings, 0 replies; 6+ messages in thread
From: Simon Marchi @ 2023-01-20 16:38 UTC (permalink / raw)
To: Andrew Burgess, Simon Marchi via Gdb-patches; +Cc: Simon Marchi
>> @@ -67,3 +90,5 @@ gdb_test_no_output "set language pascal"
>>
>> gdb_test "ptype TByteArray" \
>> "type = array \\\[0\\.\\.191\\\] of byte"
>> +gdb_test "ptype subrange_with_buggy_negative_bounds_variable" \
>> + "type = -16..-12"
>
> Should be "type = -16\\.\\.-12"
Indeed, fixed.
> Otherwise, looks good.
Thanks, will push.
Simon
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] gdb/dwarf: fix UBsan crash in read_subrange_type
2023-01-20 13:03 ` Andrew Burgess
@ 2023-01-20 16:51 ` Simon Marchi
0 siblings, 0 replies; 6+ messages in thread
From: Simon Marchi @ 2023-01-20 16:51 UTC (permalink / raw)
To: Andrew Burgess, Simon Marchi via Gdb-patches; +Cc: Simon Marchi
>> @@ -17684,15 +17683,25 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
>> with GCC, for instance, where the ambiguous DW_FORM_dataN form
>> is used instead. To work around that ambiguity, we treat
>> the bounds as signed, and thus sign-extend their values, when
>> - the base type is signed. */
>> - negative_mask =
>> - -((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
>> - if (low.kind () == PROP_CONST
>> - && !base_type->is_unsigned () && (low.const_val () & negative_mask))
>> - low.set_const_val (low.const_val () | negative_mask);
>> - if (high.kind () == PROP_CONST
>> - && !base_type->is_unsigned () && (high.const_val () & negative_mask))
>> - high.set_const_val (high.const_val () | negative_mask);
>> + the base type is signed.
>> +
>> + Skip it if the base type's length is largest than ULONGEST, to avoid
>
> s/largest/larger/
Fixed.
>> @@ -92,3 +112,5 @@ gdb_test "ptype TByteArray" \
>> "type = array \\\[0\\.\\.191\\\] of byte"
>> gdb_test "ptype subrange_with_buggy_negative_bounds_variable" \
>> "type = -16..-12"
>> +gdb_test "ptype a_16_byte_subrange_variable" \
>> + "type = -9223372036854775808..9223372036854775807"
>
> As before, I'd use "\\.\\." here.
Fixed.
> Looks good with those nits fixed.
Thanks, will push.
Simon
^ permalink raw reply [flat|nested] 6+ messages in thread
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Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-01-20 5:08 [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form Simon Marchi
2023-01-20 5:08 ` [PATCH 2/2] gdb/dwarf: fix UBsan crash in read_subrange_type Simon Marchi
2023-01-20 13:03 ` Andrew Burgess
2023-01-20 16:51 ` Simon Marchi
2023-01-20 12:51 ` [PATCH 1/2] gdb/testsuite: add test for negative subrange bounds with unsigned form Andrew Burgess
2023-01-20 16:38 ` Simon Marchi
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