MIPS ELF relocation section .rel.dyn not parsed correctly and resulting in invalid symbols

[martonilles]

Describe the bug
I have the following test ELF file:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

const int NUMBER = 42;
const char VERSION[] = "11.22";
const char *VERSION2 = "22.33";


void function1 (const char* str) {
   char buffer[16];
   strcpy(buffer, str);
}

int main(int argc, char *argv[]) {
   printf("Hello %s %s\n", VERSION, VERSION2);

   exit(0);
}

Which is compiled to MIPS platform:

test-mips-64bit-le-lib: test.c
        mips64el-linux-gnuabi64-gcc-10 -o $@ -shared $^

test-mips-64bit-le-lib.zip

This has the following relocation section:

Relocation section '.rel.dyn' at offset 0x818 contains 3 entries:
    Offset             Info             Type               Symbol's Value  Symbol's Name
0000000000000000  0000000000000000 R_MIPS_NONE           
                    Type2: R_MIPS_NONE      
                    Type3: R_MIPS_NONE      
0000000000011000  0000000000001203 R_MIPS_REL32          
                    Type2: R_MIPS_64        
                    Type3: R_MIPS_NONE      
00000000000110d0  0000000000001203 R_MIPS_REL32          
                    Type2: R_MIPS_64        
                    Type3: R_MIPS_NONE      

However when parsing these relocations in max_relocation_index: idx = std::max(idx, static_cast<uint32_t>(reloc_entry->r_info >> shift));

This results in an idx of 51511296

And therefore:

    - Number of symbols counted: 51511297
    - Table Offset:              0x530
    - String Table Offset:       0x6b0

So it try to read 51511297 symbols, which is incorrect and results in a parsing error till EOF is reached. (Also many Symbol's name #16 is empty! like logs).

There are also relocation parsing error logs: Unable to find the symbol associated with the relocation (idx: 51511296) 11000 MIPS_NONE 0 0 3120000 DYNAMIC

Not sure exactly how to fix this, elf-utils also has hard time parsing it:

Relocation section [10] '.rel.dyn' at offset 0x818 contains 3 entries:
  Offset              Type                 Value               Name
  000000000000000000  <INVALID RELOC>      000000000000000000  
  0x0000000000011000  <INVALID RELOC>      <INVALID SYMBOL 51511296>
  0x00000000000110d0  <INVALID RELOC>      <INVALID SYMBOL 51511296>

I think when parsing reloc_entry->r_info we should consider R_MIPS_REL32 types in a special way.

[romainthomas]

Yes, need to fix/improve the MIPS support