[Bug ld/24156] New: gcc -N -nostdlib test.c creates PT_PHDR out of range for auxiliary vector fetching of AT_PHDR

[ryan at bitlackeys dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=24156

            Bug ID: 24156
           Summary: gcc -N -nostdlib test.c creates PT_PHDR out of range
                    for auxiliary vector fetching of AT_PHDR
           Product: binutils
           Version: 2.31
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: ryan at bitlackeys dot org
  Target Milestone: ---

In older versions such as 2.24 this wasn't a problem because it did not
include an INTERP segment, therefore no auxv fetching was necessary. In newer
versions the ld-linux.so fails to find AT_PHDR on the auxv (On the stack)
because it PT_PHDR exists outside of a LOAD segment-- and lastly, the original
behavior of -N -nostdlib never included a PT_INTERP segment. Although I agree
that -N -nostdlib -static is more correct for excluding an interpreter. Still
if PT_INTERP is going to exist, the interpreter will need a valid AT_PHDR,
otherwise the program segfaults.

address@hidden:~/git/scop_virus$ ld -v
GNU ld (GNU Binutils for Ubuntu) 2.30
address@hidden:~/git/scop_virus$ 

address@hidden:~/git/scop_virus$ gcc -N -nostdlib t.c -o t
address@hidden:~/git/scop_virus$ readelf -l t

Elf file type is EXEC (Executable file)
Entry point 0x400241
There are 7 program headers, starting at offset 64

Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  PHDR           0x0000000000000040 0x0000000000200040 0x0000000000000000
                 0x0000000000000188 0x0000000000000188  R      0x8
readelf: Error: the PHDR segment is not covered by a LOAD segment
  INTERP         0x00000000000001c8 0x00000000004001c8 0x00000000004001c8
                 0x000000000000001c 0x000000000000001c  R      0x1
      [Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]
  LOAD           0x00000000000001c8 0x00000000004001c8 0x00000000004001c8
                 0x00000000000001b0 0x00000000000001b0  RWE    0x8
  DYNAMIC        0x0000000000000298 0x0000000000400298 0x0000000000400298
                 0x00000000000000e0 0x00000000000000e0  RW     0x8
  NOTE           0x00000000000001e4 0x00000000004001e4 0x00000000004001e4
                 0x0000000000000024 0x0000000000000024  R      0x4
  GNU_EH_FRAME   0x0000000000000248 0x0000000000400248 0x0000000000400248
                 0x0000000000000014 0x0000000000000014  R      0x4
  GNU_STACK      0x0000000000000000 0x0000000000000000 0x0000000000000000
                 0x0000000000000000 0x0000000000000000  RW     0x10

 Section to Segment mapping:
  Segment Sections...
   00     
   01     .interp 
   02     .interp .note.gnu.build-id .gnu.hash .dynsym .dynstr .text
.eh_frame_hdr .eh_frame .dynamic 
   03     .dynamic 
   04     .note.gnu.build-id 
   05     .eh_frame_hdr 
   06     
address@hidden:~/git/scop_virus$ LD_SHOW_AUXV=1 ./t
AT_SYSINFO_EHDR: 0x7ffeaa5ba000
AT_HWCAP:        bfebfbff
AT_PAGESZ:       4096
AT_CLKTCK:       100
AT_PHDR:         0x400040
AT_PHENT:        56
AT_PHNUM:        7
AT_BASE:         0x7f7d95c61000
AT_FLAGS:        0x0
AT_ENTRY:        0x400241
AT_UID:          1000
AT_EUID:         1000
AT_GID:          1000
AT_EGID:         1000
AT_SECURE:       0
AT_RANDOM:       0x7ffeaa4eecd9
AT_HWCAP2:       0x0
AT_EXECFN:       ./t
AT_PLATFORM:     x86_64
Segmentation fault (core dumped)
address@hidden:~/git/scop_virus$

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