[Bug ada/29386] New: UBSan crash in gdb.ada/arrayptr.exp

[Bug ada/29386] New: UBSan crash in gdb.ada/arrayptr.exp

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=29386

            Bug ID: 29386
           Summary: UBSan crash in gdb.ada/arrayptr.exp
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ada
          Assignee: unassigned at sourceware dot org
          Reporter: simark at simark dot ca
  Target Milestone: ---

On Ubuntu 22.04, with the `gnat-11` package installed (not `gnat`), I get:

$ ./gdb -q --data-directory=data-directory -nx
testsuite/outputs/gdb.ada/arrayptr/foo -ex "break foo.adb:40"
Reading symbols from testsuite/outputs/gdb.ada/arrayptr/foo...
/home/simark/src/binutils-gdb/gdb/dwarf2/read.c:17563:20: runtime error: shift
exponent 127 is too large for 64-bit type 'long unsigned int'

It's this line in dwarf2/read.c:

│    17562    negative_mask =                                                  
                                                                               
                                 │
│  > 17563      -((ULONGEST) 1 << (TYPE_LENGTH (base_type) * TARGET_CHAR_BIT -
1));    

That crashes, while reading this DWARF:

0x00001a2e:       DW_TAG_member
                    DW_AT_name [DW_FORM_strp]   ("OBJECT")
                    DW_AT_decl_file [DW_FORM_data1]    
("/home/simark/src/binutils-gdb/gdb/testsuite/gdb.ada/arrayptr/foo.adb")
                    DW_AT_decl_line [DW_FORM_data1]     (33)
                    DW_AT_decl_column [DW_FORM_data1]   (0x09)
                    DW_AT_type [DW_FORM_ref4]   (0x00001a3c
"foo__packed_array___XP7___XDLU_0__1180591620717411303423")
                    DW_AT_bit_size [DW_FORM_data1]      (0x46)
                    DW_AT_data_bit_offset [DW_FORM_data1]       (0x00)

0x00001a3c:       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]   (0x00001b1c
"long_long_long_unsigned")
                    DW_AT_GNAT_descriptive_type [DW_FORM_ref4]  (0x00001a5a)
                    DW_AT_artificial [DW_FORM_flag_present]     (true)

0x00001b1c:   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)

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[Bug ada/29386] UBSan crash in gdb.ada/arrayptr.exp

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29386

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
                 CC|                            |tromey at sourceware dot org
             Status|NEW                         |RESOLVED

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
This was fixed by

commit b70bff5ea52550c7cd48af7579a75ac2624ec13d
Author: Simon Marchi <simon.marchi@polymtl.ca>
Date:   Fri Jan 20 11:51:54 2023 -0500

    gdb/dwarf: fix UBsan crash in read_subrange_type

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