Re: BSD grep dumps core

[Steve Kargl]

On Mon, Aug 01, 2016 at 06:22:16PM +0200, Dimitry Andric wrote:
> On 31 Jul 2016, at 17:37, Steve Kargl  
> wrote:
> > Script started on Sun Jul 31 08:30:56 2016
> > troutmask:sgk[200] cd gcc/gcc7
> > troutmask:sgk[201] svn status
> > ?   7.diff
> > ?   decl.c.diff
> > ?   gcc/fortran/old
> > ?   gcc/fortran/pr38351.diff
> > ?   gcc/fortran/pr41922.diff
> > ?   gcc/fortran/pr69860.diff
> > ?   trans-decl.c.diff
> > ?   typescript
> > ?   z1.diff
> > troutmask:sgk[202] svn status | grep -v -E ^\?
> > Segmentation fault (core dumped)
> > troutmask:sgk[203] svn status | grep -v -E ^"\?"
> > troutmask:sgk[204] exit
> > exit
> > 
> > Script done on Sun Jul 31 08:31:54 2016
> > 
> > The core dump happens with both tcsh and sh.
> > 
> > The following works as expected
> > 
> > troutmask:sgk[202] svn status | gnugrep -v -E ^\?
> 
> Yes, '^?' is an invalid extended regular expression, but GNU grep does
> not complain about it, and simply discards the '?' character.  Our BSD
> grep dies because it also attempts to discard, but then some later logic
> goes beyond the end of the buffer.
> 
> Please try this fix:
> 
> Index: usr.bin/grep/regex/tre-fastmatch.c
> ===
> --- usr.bin/grep/regex/tre-fastmatch.c  (revision 303551)
> +++ usr.bin/grep/regex/tre-fastmatch.c  (working copy)
> @@ -621,7 +621,7 @@ tre_compile_fast(fastmatch_t *fg, const tre_char_t
>   case TRE_CHAR('+'):
>   case TRE_CHAR('?'):
> if ((cflags & REG_EXTENDED) && (i == 0))
> - continue;
> + goto badpat;
> else if ((cflags & REG_EXTENDED) ^ !escaped)
>   STORE_CHAR;
> else
> 
> After this, bsdgrep errors out with:
> 
> % bsdgrep -E '^?'
> bsdgrep: Invalid preceding regular expression
> 
> which is much saner IMHO.
> 

Dimitry,

Thanks for the quick patch.  Yes, the patch works as advertised.
I agree that an error message is preferredi/saner than a segfault.

-- 
Steve
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Re: BSD grep dumps core

[Dimitry Andric]

On 31 Jul 2016, at 17:37, Steve Kargl  wrote:
> 
> Script started on Sun Jul 31 08:30:56 2016
> troutmask:sgk[200] cd gcc/gcc7
> troutmask:sgk[201] svn status
> ?   7.diff
> ?   decl.c.diff
> ?   gcc/fortran/old
> ?   gcc/fortran/pr38351.diff
> ?   gcc/fortran/pr41922.diff
> ?   gcc/fortran/pr69860.diff
> ?   trans-decl.c.diff
> ?   typescript
> ?   z1.diff
> troutmask:sgk[202] svn status | grep -v -E ^\?
> Segmentation fault (core dumped)
> troutmask:sgk[203] svn status | grep -v -E ^"\?"
> troutmask:sgk[204] exit
> exit
> 
> Script done on Sun Jul 31 08:31:54 2016
> 
> The core dump happens with both tcsh and sh.
> 
> The following works as expected
> 
> troutmask:sgk[202] svn status | gnugrep -v -E ^\?

Yes, '^?' is an invalid extended regular expression, but GNU grep does
not complain about it, and simply discards the '?' character.  Our BSD
grep dies because it also attempts to discard, but then some later logic
goes beyond the end of the buffer.

Please try this fix:

Index: usr.bin/grep/regex/tre-fastmatch.c
===
--- usr.bin/grep/regex/tre-fastmatch.c  (revision 303551)
+++ usr.bin/grep/regex/tre-fastmatch.c  (working copy)
@@ -621,7 +621,7 @@ tre_compile_fast(fastmatch_t *fg, const tre_char_t
  case TRE_CHAR('+'):
  case TRE_CHAR('?'):
if ((cflags & REG_EXTENDED) && (i == 0))
- continue;
+ goto badpat;
else if ((cflags & REG_EXTENDED) ^ !escaped)
  STORE_CHAR;
else

After this, bsdgrep errors out with:

% bsdgrep -E '^?'
bsdgrep: Invalid preceding regular expression

which is much saner IMHO.

-Dimitry



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BSD grep dumps core

[Steve Kargl]

Script started on Sun Jul 31 08:30:56 2016
troutmask:sgk[200] cd gcc/gcc7
troutmask:sgk[201] svn status
?   7.diff
?   decl.c.diff
?   gcc/fortran/old
?   gcc/fortran/pr38351.diff
?   gcc/fortran/pr41922.diff
?   gcc/fortran/pr69860.diff
?   trans-decl.c.diff
?   typescript
?   z1.diff
troutmask:sgk[202] svn status | grep -v -E ^\?
Segmentation fault (core dumped)
troutmask:sgk[203] svn status | grep -v -E ^"\?"
troutmask:sgk[204] exit
exit

Script done on Sun Jul 31 08:31:54 2016

The core dump happens with both tcsh and sh.

The following works as expected

troutmask:sgk[202] svn status | gnugrep -v -E ^\?

-- 
Steve
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