[Bug gold/13288] New: gold silently accepts truncated ELF input

[zub at linux dot fjfi.cvut.cz]

http://sourceware.org/bugzilla/show_bug.cgi?id=13288

             Bug #: 13288
           Summary: gold silently accepts truncated ELF input
           Product: binutils
           Version: 2.23 (HEAD)
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gold
        AssignedTo: address@hidden
        ReportedBy: address@hidden
                CC: address@hidden
    Classification: Unclassified


Created attachment 5980
  --> http://sourceware.org/bugzilla/attachment.cgi?id=5980
Truncated object that ld.gold silently accepts.

gold silently accepts truncated input file (tested with ELF64 on amd64).

Example of how to reproduce:

# compile trivial source file
$ echo "int foo(void) { return 42; }" > foo.c
$ gcc -c foo.c

# create a truncated version of the object
# just cutting off one byte creates a broken file,
# but gold seems to accept even worse corruption
$ stat foo.o | grep Size
  Size: 1216          Blocks: 8          IO Block: 4096   regular file
$ dd if=foo.o of=foo-truncated.o bs=1215 count=1
1+0 records in
1+0 records out
1215 bytes (1.2 kB) copied, 0.000272381 s, 4.5 MB/s

# verify that the file is indeed corrupted
$ readelf -a foo-truncated.o > /dev/null
readelf: Error: Unable to read in 0x18 bytes of relocs
$ objdump -r foo-truncated.o 

foo-truncated.o:     file format elf64-x86-64

RELOCATION RECORDS FOR [.eh_frame]:objdump: foo-truncated.o: File truncated

# now ask gold to relink it:
$ ld.gold -r foo-truncated.o -o relinked.o
$

# by the way ld.bfd correctly rejects the file:
$ ld.bfd -r foo-truncated.o -o relinked.o
foo-truncated.o: could not read symbols: File truncated


This can cause difficult-to-track-down issues if an object in larger project is
corrupted.

(Attaching the exact file I used to reproduce this issue, as the object is
compiler dependent and you could possibly get different results with different
object.)

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