Re: [devel] [SCM] packages/bash3: heads/p9

[Alexey Appolonov <alexey@altlinux.org>]

03.11.2020 01:18, Dmitry V. Levin пишет:
> On Fri, Oct 30, 2020 at 09:35:43PM +0000, Alexey Appolonov wrote:
>> Update of /people/alexey/packages/bash3.git
> [...]
>> commit 0db3057724a11b6e9f3bdca6a831370443aaa06e
>> Author: Alexey Appolonov <alexey@altlinux.org>
>> Date:   Tue Oct 27 14:36:56 2020 +0300
>>
>>      Preventing a segmentation fault in '_evalfile' func of 'evalfile.c'
>>      
>>      Index 'result' can be -1; The index is checked from the top also
>>      (just in case).
> Prevent a potential segmentation fault ...
>
>> commit 6c6399d5a7cb51ae53c196f0bfdfd92e43711544
>> Author: Alexey Appolonov <alexey@altlinux.org>
>> Date:   Tue Oct 27 13:53:08 2020 +0300
>>
>>      Preventing a segmentation fault in 'make_redirection' func of 'make_cmd.c'
>>      
>>      Index 'wlen' is -1 if a length of 'w->word' C-string is 0.
> Likewise.
>
> [...]
>> diff --git a/bash/builtins/evalfile.c b/bash/builtins/evalfile.c
>> index d05bc7b..9eec1a5 100644
>> --- a/bash/builtins/evalfile.c
>> +++ b/bash/builtins/evalfile.c
>> @@ -149,7 +149,8 @@ file_error_and_exit:
>>   
>>     string = (char *)xmalloc (1 + file_size);
>>     result = read (fd, string, file_size);
>> -  string[result] = '\0';
>> +  if (result >= 0 && result <= file_size)
>> +    string[result] = '\0';
>>   
>>     return_val = errno;
>>     close (fd);
> Adding a check for result <= file_size?  Really?  Do you suppose that
> read (fd, string, file_size) is ever capable of returning a value
> greater than file_size?

I just think that the comfort of having such checks outweighs
the negligible computational costs that they bring.

>> diff --git a/bash/make_cmd.c b/bash/make_cmd.c
>> index c819b27..bb33da2 100644
>> --- a/bash/make_cmd.c
>> +++ b/bash/make_cmd.c
>> @@ -731,7 +731,12 @@ make_redirection (source, instruction, dest_and_filename)
>>       case r_duplicating_output_word:	/* 1>&$foo */
>>         w = dest_and_filename.filename;
>>         wlen = strlen (w->word) - 1;
>> -      if (w->word[wlen] == '-')		/* Yuck */
>> +      if (wlen < 0)
>> +        {
>> +          programming_error (_("make_redirection: redirection instruction `%d' for an empty file name"), instruction);
>> +          abort ();
>> +        }
>> +      else if (w->word[wlen] == '-')	/* Yuck */
>>           {
>>             w->word[wlen] = '\0';
>>   	  if (all_digits (w->word) && legal_number (w->word, &lfd) && lfd == (int)lfd)
> A programming error?  Is it ever possible to reach the code added by this hunk?

It is if "strlen (w->word)" equals 0.

The "programming_error" function is used to handle another unlikely scenario
(see just below in the code).

>> @@ -743,7 +748,6 @@ make_redirection (source, instruction, dest_and_filename)
>>   	  else
>>   	    temp->instruction = (instruction == r_duplicating_input_word) ? r_move_input_word : r_move_output_word;
>>           }
>> -
>>         break;
>>   
>>       default:
> Do you really need to change spacings in bash3?

I find it quite distracting in this particular case. And it didn't match
the code style anyway.