From 175299b5bd364006a609e232b93a3dfb76e59d78 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Fri, 14 Oct 2022 17:14:54 -0300 Subject: [PATCH] cifs: fix double-fault crash during ntlmssp The crash occurred because we were calling memzero_explicit() on an already freed sess_data::iov[1] (ntlmsspblob) in sess_free_buffer(). Fix this by not calling memzero_explicit() on sess_data::iov[1] as it's already by handled by callers. Fixes: 51865fc04b82 ("cifs: replace kfree() with kfree_sensitive() for sensitive data") Reviewed-by: Enzo Matsumiya Signed-off-by: Paulo Alcantara (SUSE) Signed-off-by: Steve French --- fs/cifs/sess.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c index c9edec7081de7..0435d1dfa9e11 100644 --- a/fs/cifs/sess.c +++ b/fs/cifs/sess.c @@ -1208,16 +1208,18 @@ out_free_smb_buf: static void sess_free_buffer(struct sess_data *sess_data) { - int i; + struct kvec *iov = sess_data->iov; - /* 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); + /* + * Zero the session data before freeing, as it might contain sensitive info (keys, etc). + * Note that iov[1] is already freed by caller. + */ + if (sess_data->buf0_type != CIFS_NO_BUFFER && iov[0].iov_base) + memzero_explicit(iov[0].iov_base, iov[0].iov_len); - free_rsp_buf(sess_data->buf0_type, sess_data->iov[0].iov_base); + free_rsp_buf(sess_data->buf0_type, iov[0].iov_base); sess_data->buf0_type = CIFS_NO_BUFFER; - kfree(sess_data->iov[2].iov_base); + kfree_sensitive(iov[2].iov_base); } static int -- 2.39.5