[Bug binutils/23694] New: readelf doesn't handle empty .bss section correctly

[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=23694

            Bug ID: 23694
           Summary: readelf doesn't handle empty .bss section correctly
           Product: binutils
           Version: 2.32 (HEAD)
            Status: NEW
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: hjl.tools at gmail dot com
  Target Milestone: ---

Created attachment 11267
  --> https://sourceware.org/bugzilla/attachment.cgi?id=11267&action=edit
A testcase

address@hidden binutils]$ ./readelf -WlS /tmp/dump
There are 12 section headers, starting at offset 0x8544:

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf
Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0 
0
  [ 1] .text             PROGBITS        00008000 0000b4 000004 00  AX  0   0 
4
  [ 2] .bss              NOBITS          00010004 0080dc 000000 00  WA  0   0 
1
  [ 3] .note.4           NOTE            00010078 008150 000028 00   A  0   0 
8
  [ 4] .note.1           NOTE            000100a0 008178 000028 00   A  0   0 
8
  [ 5] .note.gnu.build-id NOTE            00010004 0080b8 000024 00   A  0   0 
4
  [ 6] .note.2           NOTE            00010028 008100 000028 00   A  0   0 
4
  [ 7] .note.3           NOTE            00010050 008128 000028 00   A  0   0 
4
  [ 8] .ARM.attributes   ARM_ATTRIBUTES  00000000 0081a0 000014 00      0   0 
1
  [ 9] .symtab           SYMTAB          00000000 0081b4 000260 10     10  24 
4
  [10] .strtab           STRTAB          00000000 008414 0000c5 00      0   0 
1
  [11] .shstrtab         STRTAB          00000000 0084d9 000069 00      0   0 
1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  y (purecode), p (processor specific)

Elf file type is EXEC (Executable file)
Entry point 0x8000
There are 4 program headers, starting at offset 52

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  LOAD           0x0000b4 0x00008000 0x00008000 0x08028 0x08028 R E 0x4
  LOAD           0x0080dc 0x00010004 0x00010004 0x000c4 0x000c4 RW  0x8
  NOTE           0x008150 0x00010078 0x00010078 0x00050 0x00050 R   0x8
  NOTE           0x0080b8 0x00010004 0x00010004 0x00098 0x00074 R   0x4

 Section to Segment mapping:
  Segment Sections...
   00     .text .bss .note.gnu.build-id 
   01     .bss .note.4 .note.1 .note.2 .note.3 
   02     .note.4 .note.1 
   03     .bss .note.gnu.build-id .note.2 .note.3 
address@hidden binutils]$ 

Since .bss section is empty, it shouldn't be included in PT_NOTE segment:

address@hidden binutils]$ eu-readelf -WlS /tmp/dump
There are 12 section headers, starting at offset 0x8544:

Section Headers:
[Nr] Name                 Type         Addr     Off    Size   ES Flags Lk Inf
Al
[ 0]                      NULL         00000000 000000 000000  0        0   0 
0
[ 1] .text                PROGBITS     00008000 0000b4 000004  0 AX     0   0 
4
[ 2] .bss                 NOBITS       00010004 0080dc 000000  0 WA     0   0 
1
[ 3] .note.4              NOTE         00010078 008150 000028  0 A      0   0 
8
[ 4] .note.1              NOTE         000100a0 008178 000028  0 A      0   0 
8
[ 5] .note.gnu.build-id   NOTE         00010004 0080b8 000024  0 A      0   0 
4
[ 6] .note.2              NOTE         00010028 008100 000028  0 A      0   0 
4
[ 7] .note.3              NOTE         00010050 008128 000028  0 A      0   0 
4
[ 8] .ARM.attributes      ARM_ATTRIBUTES 00000000 0081a0 000014  0        0   0
 1
[ 9] .symtab              SYMTAB       00000000 0081b4 000260 16       10  24 
4
[10] .strtab              STRTAB       00000000 008414 0000c5  0        0   0 
1
[11] .shstrtab            STRTAB       00000000 0084d9 000069  0        0   0 
1

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz  MemSiz   Flg Align
  LOAD           0x0000b4 0x00008000 0x00008000 0x008028 0x008028 R E 0x4
  LOAD           0x0080dc 0x00010004 0x00010004 0x0000c4 0x0000c4 RW  0x8
  NOTE           0x008150 0x00010078 0x00010078 0x000050 0x000050 R   0x8
  NOTE           0x0080b8 0x00010004 0x00010004 0x000098 0x000074 R   0x4

 Section to Segment mapping:
  Segment Sections...
   00      [RO: .text .note.gnu.build-id]
   01      .note.4 .note.1 [RO: .note.gnu.build-id] .note.2 .note.3
   02      .note.4 .note.1
   03      [RO: .note.gnu.build-id] .note.2 .note.3
address@hidden binutils]$

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