The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x e7067a446264a7514fa1cfaa4052cdb6803bc6a2 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023041754-retread-approach-96af@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

e7067a446264 ("ksmbd: avoid out of bounds access in decode_preauth_ctxt()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e7067a446264a7514fa1cfaa4052cdb6803bc6a2 Mon Sep 17 00:00:00 2001 From: David Disseldorp ddiss@suse.de Date: Thu, 13 Apr 2023 23:49:57 +0900 Subject: [PATCH] ksmbd: avoid out of bounds access in decode_preauth_ctxt()

Confirm that the accessed pneg_ctxt->HashAlgorithms address sits within the SMB request boundary; deassemble_neg_contexts() only checks that the eight byte smb2_neg_context header + (client controlled) DataLength are within the packet boundary, which is insufficient.

Checking for sizeof(struct smb2_preauth_neg_context) is overkill given that the type currently assumes SMB311_SALT_SIZE bytes of trailing Salt.

Signed-off-by: David Disseldorp ddiss@suse.de Acked-by: Namjae Jeon linkinjeon@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Steve French stfrench@microsoft.com

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index 8af939a181be..67b7e766a06b 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -876,17 +876,21 @@ static void assemble_neg_contexts(struct ksmbd_conn *conn, }

static __le32 decode_preauth_ctxt(struct ksmbd_conn *conn, - struct smb2_preauth_neg_context *pneg_ctxt) + struct smb2_preauth_neg_context *pneg_ctxt, + int len_of_ctxts) { - __le32 err = STATUS_NO_PREAUTH_INTEGRITY_HASH_OVERLAP; + /* + * sizeof(smb2_preauth_neg_context) assumes SMB311_SALT_SIZE Salt, + * which may not be present. Only check for used HashAlgorithms[1]. + */ + if (len_of_ctxts < MIN_PREAUTH_CTXT_DATA_LEN) + return STATUS_INVALID_PARAMETER;

- if (pneg_ctxt->HashAlgorithms == SMB2_PREAUTH_INTEGRITY_SHA512) { - conn->preauth_info->Preauth_HashId = - SMB2_PREAUTH_INTEGRITY_SHA512; - err = STATUS_SUCCESS; - } + if (pneg_ctxt->HashAlgorithms != SMB2_PREAUTH_INTEGRITY_SHA512) + return STATUS_NO_PREAUTH_INTEGRITY_HASH_OVERLAP;

- return err; + conn->preauth_info->Preauth_HashId = SMB2_PREAUTH_INTEGRITY_SHA512; + return STATUS_SUCCESS; }

static void decode_encrypt_ctxt(struct ksmbd_conn *conn, @@ -1014,7 +1018,8 @@ static __le32 deassemble_neg_contexts(struct ksmbd_conn *conn, break;

status = decode_preauth_ctxt(conn, - (struct smb2_preauth_neg_context *)pctx); + (struct smb2_preauth_neg_context *)pctx, + len_of_ctxts); if (status != STATUS_SUCCESS) break; } else if (pctx->ContextType == SMB2_ENCRYPTION_CAPABILITIES) {