merged into cifs-2.6.git for-next On Tue, Sep 20, 2022 at 1:10 PM Enzo Matsumiya <ematsumiya@xxxxxxx> wrote: > > Replace kfree with kfree_sensitive, or prepend memzero_explicit() in > other cases, when freeing sensitive material that could still be left > in memory. > > Signed-off-by: Enzo Matsumiya <ematsumiya@xxxxxxx> > Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> > Link: https://lore.kernel.org/r/202209201529.ec633796-oliver.sang@xxxxxxxxx > --- > v3: fix use-after-free reported by kernel test robot (this UAF existed before this patch, > actually), adjust commit message slightly > v2: remove unnecessary NULL checks before kfree_sensitive() > > fs/cifs/cifsencrypt.c | 12 ++++++------ > fs/cifs/connect.c | 6 +++--- > fs/cifs/fs_context.c | 12 ++++++++++-- > fs/cifs/misc.c | 2 +- > fs/cifs/sess.c | 24 +++++++++++++++--------- > fs/cifs/smb2ops.c | 6 +++--- > fs/cifs/smb2pdu.c | 19 ++++++++++++++----- > 7 files changed, 52 insertions(+), 29 deletions(-) > > diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c > index 46f5718754f9..d848bc0aac27 100644 > --- a/fs/cifs/cifsencrypt.c > +++ b/fs/cifs/cifsencrypt.c > @@ -679,7 +679,7 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp) > unlock: > cifs_server_unlock(ses->server); > setup_ntlmv2_rsp_ret: > - kfree(tiblob); > + kfree_sensitive(tiblob); > > return rc; > } > @@ -753,14 +753,14 @@ cifs_crypto_secmech_release(struct TCP_Server_Info *server) > server->secmech.ccmaesdecrypt = NULL; > } > > - kfree(server->secmech.sdesccmacaes); > + kfree_sensitive(server->secmech.sdesccmacaes); > server->secmech.sdesccmacaes = NULL; > - kfree(server->secmech.sdeschmacsha256); > + kfree_sensitive(server->secmech.sdeschmacsha256); > server->secmech.sdeschmacsha256 = NULL; > - kfree(server->secmech.sdeschmacmd5); > + kfree_sensitive(server->secmech.sdeschmacmd5); > server->secmech.sdeschmacmd5 = NULL; > - kfree(server->secmech.sdescmd5); > + kfree_sensitive(server->secmech.sdescmd5); > server->secmech.sdescmd5 = NULL; > - kfree(server->secmech.sdescsha512); > + kfree_sensitive(server->secmech.sdescsha512); > server->secmech.sdescsha512 = NULL; > } > diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c > index 7ae6f2c08153..a43d5686c302 100644 > --- a/fs/cifs/connect.c > +++ b/fs/cifs/connect.c > @@ -311,7 +311,7 @@ cifs_abort_connection(struct TCP_Server_Info *server) > } > server->sequence_number = 0; > server->session_estab = false; > - kfree(server->session_key.response); > + kfree_sensitive(server->session_key.response); > server->session_key.response = NULL; > server->session_key.len = 0; > server->lstrp = jiffies; > @@ -1580,7 +1580,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect) > > cifs_crypto_secmech_release(server); > > - kfree(server->session_key.response); > + kfree_sensitive(server->session_key.response); > server->session_key.response = NULL; > server->session_key.len = 0; > kfree(server->hostname); > @@ -4134,7 +4134,7 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses, > if (ses->auth_key.response) { > cifs_dbg(FYI, "Free previous auth_key.response = %p\n", > ses->auth_key.response); > - kfree(ses->auth_key.response); > + kfree_sensitive(ses->auth_key.response); > ses->auth_key.response = NULL; > ses->auth_key.len = 0; > } > diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c > index 0e13dec86b25..45119597c765 100644 > --- a/fs/cifs/fs_context.c > +++ b/fs/cifs/fs_context.c > @@ -791,6 +791,13 @@ do { \ > cifs_sb->ctx->field = NULL; \ > } while (0) > > +#define STEAL_STRING_SENSITIVE(cifs_sb, ctx, field) \ > +do { \ > + kfree_sensitive(ctx->field); \ > + ctx->field = cifs_sb->ctx->field; \ > + cifs_sb->ctx->field = NULL; \ > +} while (0) > + > static int smb3_reconfigure(struct fs_context *fc) > { > struct smb3_fs_context *ctx = smb3_fc2context(fc); > @@ -811,7 +818,7 @@ static int smb3_reconfigure(struct fs_context *fc) > STEAL_STRING(cifs_sb, ctx, UNC); > STEAL_STRING(cifs_sb, ctx, source); > STEAL_STRING(cifs_sb, ctx, username); > - STEAL_STRING(cifs_sb, ctx, password); > + STEAL_STRING_SENSITIVE(cifs_sb, ctx, password); > STEAL_STRING(cifs_sb, ctx, domainname); > STEAL_STRING(cifs_sb, ctx, nodename); > STEAL_STRING(cifs_sb, ctx, iocharset); > @@ -1162,7 +1169,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc, > } > break; > case Opt_pass: > - kfree(ctx->password); > + kfree_sensitive(ctx->password); > ctx->password = NULL; > if (strlen(param->string) == 0) > break; > @@ -1470,6 +1477,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc, > return 0; > > cifs_parse_mount_err: > + kfree_sensitive(ctx->password); > return -EINVAL; > } > > diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c > index 87f60f736731..85109a9a2146 100644 > --- a/fs/cifs/misc.c > +++ b/fs/cifs/misc.c > @@ -1119,7 +1119,7 @@ cifs_alloc_hash(const char *name, > void > cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc) > { > - kfree(*sdesc); > + kfree_sensitive(*sdesc); > *sdesc = NULL; > if (*shash) > crypto_free_shash(*shash); > diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c > index 3af3b05b6c74..f1c3c6d9146c 100644 > --- a/fs/cifs/sess.c > +++ b/fs/cifs/sess.c > @@ -1213,6 +1213,12 @@ sess_alloc_buffer(struct sess_data *sess_data, int wct) > static void > sess_free_buffer(struct sess_data *sess_data) > { > + int i; > + > + /* zero the session data before freeing, as it might contain sensitive info (keys, etc) */ > + for (i = 0; i < 3; i++) > + if (sess_data->iov[i].iov_base) > + memzero_explicit(sess_data->iov[i].iov_base, sess_data->iov[i].iov_len); > > free_rsp_buf(sess_data->buf0_type, sess_data->iov[0].iov_base); > sess_data->buf0_type = CIFS_NO_BUFFER; > @@ -1374,7 +1380,7 @@ sess_auth_ntlmv2(struct sess_data *sess_data) > sess_data->result = rc; > sess_data->func = NULL; > sess_free_buffer(sess_data); > - kfree(ses->auth_key.response); > + kfree_sensitive(ses->auth_key.response); > ses->auth_key.response = NULL; > } > > @@ -1513,7 +1519,7 @@ sess_auth_kerberos(struct sess_data *sess_data) > sess_data->result = rc; > sess_data->func = NULL; > sess_free_buffer(sess_data); > - kfree(ses->auth_key.response); > + kfree_sensitive(ses->auth_key.response); > ses->auth_key.response = NULL; > } > > @@ -1648,7 +1654,7 @@ sess_auth_rawntlmssp_negotiate(struct sess_data *sess_data) > rc = decode_ntlmssp_challenge(bcc_ptr, blob_len, ses); > > out_free_ntlmsspblob: > - kfree(ntlmsspblob); > + kfree_sensitive(ntlmsspblob); > out: > sess_free_buffer(sess_data); > > @@ -1658,9 +1664,9 @@ sess_auth_rawntlmssp_negotiate(struct sess_data *sess_data) > } > > /* Else error. Cleanup */ > - kfree(ses->auth_key.response); > + kfree_sensitive(ses->auth_key.response); > ses->auth_key.response = NULL; > - kfree(ses->ntlmssp); > + kfree_sensitive(ses->ntlmssp); > ses->ntlmssp = NULL; > > sess_data->func = NULL; > @@ -1759,7 +1765,7 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data) > } > > out_free_ntlmsspblob: > - kfree(ntlmsspblob); > + kfree_sensitive(ntlmsspblob); > out: > sess_free_buffer(sess_data); > > @@ -1767,9 +1773,9 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data) > rc = sess_establish_session(sess_data); > > /* Cleanup */ > - kfree(ses->auth_key.response); > + kfree_sensitive(ses->auth_key.response); > ses->auth_key.response = NULL; > - kfree(ses->ntlmssp); > + kfree_sensitive(ses->ntlmssp); > ses->ntlmssp = NULL; > > sess_data->func = NULL; > @@ -1845,7 +1851,7 @@ int CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses, > rc = sess_data->result; > > out: > - kfree(sess_data); > + kfree_sensitive(sess_data); > return rc; > } > #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */ > diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c > index 421be43af425..5094336cade6 100644 > --- a/fs/cifs/smb2ops.c > +++ b/fs/cifs/smb2ops.c > @@ -4410,11 +4410,11 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst, > if (!rc && enc) > memcpy(&tr_hdr->Signature, sign, SMB2_SIGNATURE_SIZE); > > - kfree(iv); > + kfree_sensitive(iv); > free_sg: > - kfree(sg); > + kfree_sensitive(sg); > free_req: > - kfree(req); > + kfree_sensitive(req); > return rc; > } > > diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c > index 6352ab32c7e7..722ebff05759 100644 > --- a/fs/cifs/smb2pdu.c > +++ b/fs/cifs/smb2pdu.c > @@ -1345,6 +1345,13 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data) > static void > SMB2_sess_free_buffer(struct SMB2_sess_data *sess_data) > { > + int i; > + > + /* zero the session data before freeing, as it might contain sensitive info (keys, etc) */ > + for (i = 0; i < 2; i++) > + if (sess_data->iov[i].iov_base) > + memzero_explicit(sess_data->iov[i].iov_base, sess_data->iov[i].iov_len); > + > free_rsp_buf(sess_data->buf0_type, sess_data->iov[0].iov_base); > sess_data->buf0_type = CIFS_NO_BUFFER; > } > @@ -1477,6 +1484,8 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data) > out_put_spnego_key: > key_invalidate(spnego_key); > key_put(spnego_key); > + if (rc) > + kfree_sensitive(ses->auth_key.response); > out: > sess_data->result = rc; > sess_data->func = NULL; > @@ -1573,7 +1582,7 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data) > } > > out: > - kfree(ntlmssp_blob); > + memzero_explicit(ntlmssp_blob, blob_length); > SMB2_sess_free_buffer(sess_data); > if (!rc) { > sess_data->result = 0; > @@ -1581,7 +1590,7 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data) > return; > } > out_err: > - kfree(ses->ntlmssp); > + kfree_sensitive(ses->ntlmssp); > ses->ntlmssp = NULL; > sess_data->result = rc; > sess_data->func = NULL; > @@ -1657,9 +1666,9 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data) > } > #endif > out: > - kfree(ntlmssp_blob); > + memzero_explicit(ntlmssp_blob, blob_length); > SMB2_sess_free_buffer(sess_data); > - kfree(ses->ntlmssp); > + kfree_sensitive(ses->ntlmssp); > ses->ntlmssp = NULL; > sess_data->result = rc; > sess_data->func = NULL; > @@ -1737,7 +1746,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses, > cifs_server_dbg(VFS, "signing requested but authenticated as guest\n"); > rc = sess_data->result; > out: > - kfree(sess_data); > + kfree_sensitive(sess_data); > return rc; > } > > -- > 2.35.3 > -- Thanks, Steve
