Re: [PATCH] ldconfig: Fix memory leaks

[Siddhesh Poyarekar <siddhesh@sourceware.org>]

On 5/17/21 10:45 PM, Adhemerval Zanella wrote:
> 
> 
> On 11/05/2021 14:16, Siddhesh Poyarekar via Libc-alpha wrote:
>> Coverity discovered that paths allocated by chroot_canon are not freed
>> in a couple of routines in ldconfig.
> 
> LGTM, just a clarification about a specific change below.
> 
> As a side note, reviewing this patch I think chroot_canon can be replaced
> with realpath.

I'll post a separate patch for it.

> 
> Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
> 
>> ---
>>   elf/ldconfig.c | 23 +++++++++++++++--------
>>   1 file changed, 15 insertions(+), 8 deletions(-)
>>
>> diff --git a/elf/ldconfig.c b/elf/ldconfig.c
>> index 28ed637a29..3192aa49d9 100644
>> --- a/elf/ldconfig.c
>> +++ b/elf/ldconfig.c
>> @@ -693,8 +693,7 @@ manual_link (char *library)
>>         if (real_path == NULL)
>>   	{
>>   	  error (0, errno, _("Can't find %s"), path);
>> -	  free (path);
>> -	  return;
>> +	  goto out;
>>   	}
>>         real_library = alloca (strlen (real_path) + strlen (libname) + 2);
>>         sprintf (real_library, "%s/%s", real_path, libname);
> 
> Why do you need this since 'real_path' does not need to be freed here ?

You're right, it's unnecessary, I'll revert this hunk.

> 
>> @@ -709,16 +708,14 @@ manual_link (char *library)
>>     if (lstat64 (real_library, &stat_buf))
>>       {
>>         error (0, errno, _("Cannot lstat %s"), library);
>> -      free (path);
>> -      return;
>> +      goto out;
>>       }
>>     /* We don't want links here!  */
> 
> Ok.
> 
>>     else if (!S_ISREG (stat_buf.st_mode))
>>       {
>>         error (0, 0, _("Ignored file %s since it is not a regular file."),
>>   	     library);
>> -      free (path);
>> -      return;
>> +      goto out;
>>       }
>>   
> 
> Ok.
> 
>>     if (process_file (real_library, library, libname, &flag, &osversion,
>> @@ -726,14 +723,16 @@ manual_link (char *library)
>>       {
>>         error (0, 0, _("No link created since soname could not be found for %s"),
>>   	     library);
>> -      free (path);
>> -      return;
>> +      goto out;
>>       }
> 
> Ok.
> 
>>     if (soname == NULL)
>>       soname = implicit_soname (libname, flag);
>>     create_links (real_path, path, libname, soname);
>>     free (soname);
>> +out:
>>     free (path);
>> +  if (path != real_path)
>> +    free (real_path);
>>   }
>>   
>>   
> 
> Ok.
> 
>> @@ -920,8 +919,16 @@ search_dir (const struct dir_entry *entry)
>>   	      /* Remove stale symlinks.  */
>>   	      if (opt_link && strstr (direntry->d_name, ".so."))
>>   		unlink (real_file_name);
>> +
>> +	      if (opt_chroot)
>> +		free (target_name);
>> +
> 
> Ok, 'opt_chroot' being not null means it was allocated using chroot_canon
> instead of alloca.  No implicit checks though.

OK, fixed.


Thanks,
Siddhesh