Re: [PATCH 4/5] smb: client: Clear sensitive stack data in smb1encrypt.c

On 18/08/2026 07.58, Namjae Jeon wrote:
> On Wed, Aug 12, 2026 at 10:13 PM Thomas Huth <[email protected]> wrote:
>>
>> From: Thomas Huth <[email protected]>
>>
>> Make sure to not leak signature data via the stack, clear it
>> with memzero_explicit() before leaving the function.
>>
>> To avoid that we have to introduce "goto"-cleanup here, we re-arrange
>> the code a little bit (and drop the commented cifs_dump_mem debug
>> code that looks like a leftover from very early days).
>>
>> Signed-off-by: Thomas Huth <[email protected]>
>> ---
>>   fs/smb/client/smb1encrypt.c | 19 +++++++++----------
>>   1 file changed, 9 insertions(+), 10 deletions(-)
>>
>> diff --git a/fs/smb/client/smb1encrypt.c b/fs/smb/client/smb1encrypt.c
>> index bf10fdeeedcab..c9eb68f04e7b0 100644
>> --- a/fs/smb/client/smb1encrypt.c
>> +++ b/fs/smb/client/smb1encrypt.c
>> @@ -81,6 +81,7 @@ int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
>>          else
>>                  memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);
>>
>> +       memzero_explicit(smb_signature, sizeof(smb_signature));
>>          return rc;
>>   }
>>
>> @@ -126,15 +127,13 @@ int cifs_verify_signature(struct smb_rqst *rqst,
>>          rc = cifs_calc_signature(rqst, server, what_we_think_sig_should_be);
>>          cifs_server_unlock(server);
> The MD5 context in  cifs_calc_signature()  may remain uncleared when
> __cifs_calc_signature()  fails.
> 
> rc = __cifs_calc_signature(...);
>                                                 ┃
> memzero_explicit(&ctx, sizeof(ctx));
My plan was to handle that via a __cleanup() function, too, but I need to 
get that merged first:

  https://lore.kernel.org/lkml/[email protected]/

  Thomas