[Bug general/23786] New: Divide-by-zero Problem in function arlib_add_symbols() in arlib.c in elfutils-0.174

wcventure at 126 dot com sourceware-bugzilla@sourceware.org
Wed Oct 17 08:37:00 GMT 2018


https://sourceware.org/bugzilla/show_bug.cgi?id=23786

            Bug ID: 23786
           Summary: Divide-by-zero Problem in function arlib_add_symbols()
                    in arlib.c in elfutils-0.174
           Product: elfutils
           Version: unspecified
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: general
          Assignee: unassigned at sourceware dot org
          Reporter: wcventure at 126 dot com
                CC: elfutils-devel at sourceware dot org
  Target Milestone: ---

Hi,

I found some floating point exception in function arlib_add_symbols() in
arlib.c of the latest elfutils-0.174 code base. I have confirmed them with GDB
and Address Sanitizer.

Here are the POC files. Please use " ./eu-ranlib $POC " to reproduce this bug.
I'll also show you the debugging process. It seems that this is caused by the
divide-by-zero. 

In arlib.c:255, there exist a division calculation:

> int nsyms = shdr->sh_size / shdr->sh_entsize;

I can provide you some testcases to make shdr->sh_entsize = 0. And you can use
the testcases to reproduce the bug. Divide by zero is bad. We need to make a
check before doing division calculation.

--- Comment #1 from wcventure <wcventure at 126 dot com> ---
Created attachment 11336
  --> https://sourceware.org/bugzilla/attachment.cgi?id=11336&action=edit
POC1

I have also confirmed them with Address Sanitizer.
The ASAN dumps the stack trace as follows:
ASAN:DEADLYSIGNAL
=================================================================
==2496==ERROR: AddressSanitizer: FPE on unknown address 0x0000004065d8 (pc
0x0000004065d8 bp 0x7ffd4c109620 sp 0x7ffd4c109550 T0)
    #0 0x4065d7 in arlib_add_symbols
/media/hjwang/01D3344861A8D2E0/wcventure/Project/elfutils/src/arlib.c:255
    #1 0x4029c5 in handle_file
/media/hjwang/01D3344861A8D2E0/wcventure/Project/elfutils/src/ranlib.c:193
    #2 0x4029c5 in main
/media/hjwang/01D3344861A8D2E0/wcventure/Project/elfutils/src/ranlib.c:110
    #3 0x7fc97b51982f in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #4 0x403d28 in _start
(/media/hjwang/01D3344861A8D2E0/wcventure/Project/elfutils/build/bin/eu-ranlib+0x403d28)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: FPE
/media/hjwang/01D3344861A8D2E0/wcventure/Project/elfutils/src/arlib.c:255 in
arlib_add_symbols
==2496==ABORTING
Aborted

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