Re: [PATCH] test-container: Use nftw instead of rm -rf

[Stefan Liebler <stli@linux.ibm.com>]

On 28.09.23 13:11, Adhemerval Zanella Netto wrote:
> 
> 
> On 28/09/23 06:40, Stefan Liebler wrote:
>> On 27.09.23 21:20, Adhemerval Zanella wrote:
>>> If the binary to run is 'env', test-containers skips it and adds
>>> any required environment variable on the process envs variables.
>>> This simplifies the required code to spawn new process (no need
>>> to build an env-like program).
>>>
>>> However, this is an issue for recursive_remove if there is any
>>> LD_PRELOAD, since test-container will not prepend the loader command
>>> along with required paths.  If the required preloaded library can
>>> not be loaded by the system glibc, the 'post-clean rsync' will
>>> eventually fail.
>>>
>>> One example is if system glibc does not support DT_RELR and the
>>> built glibc does, the nss/tst-nss-gai-hv2-canonname test fails
>>> with:
>>>
>>> ../scripts/evaluate-test.sh nss/tst-nss-gai-hv2-canonname $? false false
>>> 86_64-linux-gnu/nss/tst-nss-gai-hv2-canonname.test-result
>>> rm: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_ABI_DT_RELR' not
>>> found (required by x86_64-linux-gnu/malloc/libc_malloc_debug.so)
>>>
>>> Instead trying to figure out the required loader arguments on how
>>> to spawn the 'rm -rf', replace the command with a nftw call.
>>>
>> Just as information, I've also recognized this issue. For me (on
>> x86_64/s390x), I got "*** stack smashing detected ***: terminated" in
>> this rm due to preloading with the fresh build libc_malloc_debug.so.
>> In malloc_hook_ini -> generic_hook_ini -> initialize_malloc_check, we have:
>> TUNABLE_GET (check, int32_t, TUNABLE_CALLBACK (set_mallopt_check));
>> In __tunable_get_val, the tunables ID from current-build and system for
>> glibc.malloc.check differs. In my case it is 30, which is beyond the
>> range of the systems tunable_list[]. This leads to storing a 8byte value
>> to passed valp. Unfortunately it points to a 4 byte int32_t and the
>> other 4 bytes belong to the stack smashing canary.
> 
> Indeed the tunables might another problem, thanks for checking it.
> 
>>
>> Your patch solves the issue for me.
> 
> Is it a reviewed-by ;) ?
Yes, the patch is fine.
Reviewed-by: Stefan Liebler <stli@linux.ibm.com>
> 
>>> Checked on x86_64-linux-gnu.
>>> ---
>>>  support/test-container.c | 34 +++++++++++-----------------------
>>>  1 file changed, 11 insertions(+), 23 deletions(-)
>>>
>>> diff --git a/support/test-container.c b/support/test-container.c
>>> index 788b091ea0..95dfef1a99 100644
>>> --- a/support/test-container.c
>>> +++ b/support/test-container.c
>>> @@ -37,6 +37,7 @@
>>>  #include <errno.h>
>>>  #include <error.h>
>>>  #include <libc-pointer-arith.h>
>>> +#include <ftw.h>
>>>
>>>  #ifdef __linux__
>>>  #include <sys/mount.h>
>>> @@ -405,32 +406,19 @@ file_exists (char *path)
>>>    return 0;
>>>  }
>>>
>>> +static int
>>> +unlink_cb (const char *fpath, const struct stat *sb, int typeflag,
>>> +	   struct FTW *ftwbuf)
>>> +{
>>> +  return remove (fpath);
>>> +}
>>> +
>>>  static void
>>>  recursive_remove (char *path)
>>>  {
>>> -  pid_t child;
>>> -  int status;
>>> -
>>> -  child = fork ();
>>> -
>>> -  switch (child) {
>>> -  case -1:
>>> -    perror("fork");
>>> -    FAIL_EXIT1 ("Unable to fork");
>>> -  case 0:
>>> -    /* Child.  */
>>> -    execlp ("rm", "rm", "-rf", path, NULL);
>>> -    FAIL_EXIT1 ("exec rm: %m");
>>> -  default:
>>> -    /* Parent.  */
>>> -    waitpid (child, &status, 0);
>>> -    /* "rm" would have already printed a suitable error message.  */
>>> -    if (! WIFEXITED (status)
>>> -	|| WEXITSTATUS (status) != 0)
>>> -      FAIL_EXIT1 ("exec child returned status: %d", status);
>>> -
>>> -    break;
>>> -  }
>>> +  int r = nftw (path, unlink_cb, 1000, FTW_DEPTH | FTW_PHYS);
>>> +  if (r == -1)
>>> +    FAIL_EXIT1 ("recursive_remove failed");
>>>  }
>>>
>>>  /* Used for both rsync and the mytest.script "cp" command.  */
>>