From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 517E3221DB6; Fri, 24 Apr 2026 13:42:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038143; cv=none; b=X2itjzE3+Fm8RkLqYfBd5fW/RnPH6G5gsaCpUxLU99hly83FALs3bRjXheD6IjOHcreMhRVCzGPxfXwauu152OtSfj66CSZCSKM4aYnKQCDSssmeB/v+Yl8Dn5kqvhPZVM/gspo1RHlON/FqAdyMmpYkK8vj8NwPVBMEWh5DzaY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038143; c=relaxed/simple; bh=B4cMRZ0jSiNQuknMvnIWr5nj+SEV6C85/FumwfLDSFQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sMs6txFwaPVO1v7tPCKeALI+/ohQw9LmaCJ2QOzvMQ86D4qByySqgaIHMKDtGL6zjpZLuaAOZA3sCO6/RBkumDplTGaR/aLUF7JWzLzKxeb52Mf1LLQ0Ah9YliRIyogJDZB8AUJ5ZZNfsC9DXQVHKgtOmdewaifP08iWHwJTVL8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yVoceahB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="yVoceahB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7B63C2BCB2; Fri, 24 Apr 2026 13:42:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777038143; bh=B4cMRZ0jSiNQuknMvnIWr5nj+SEV6C85/FumwfLDSFQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yVoceahBH1SPZdgBuCQBQUS+lqPRgKYNj8aIceJeAKctPMnvRJ9GB+NMySdcVq/3r 6i6HbEi2cGtsUoLYe+k5ssWERgmAeA7Yj7C+hnacgswRR+A/C6KXDr5LZhjX+MbuaJ 0nPFhqA61Tiif2ZQn8z16XpUbqfg2QU3kTHfkznE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Michael Bommarito , Namjae Jeon , Steve French Subject: [PATCH 6.18 41/55] ksmbd: validate response sizes in ipc_validate_msg() Date: Fri, 24 Apr 2026 15:31:20 +0200 Message-ID: <20260424132438.484553517@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260424132430.006424517@linuxfoundation.org> References: <20260424132430.006424517@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Bommarito commit d6a6aa81eac2c9bff66dc6e191179cb69a14426b upstream. ipc_validate_msg() computes the expected message size for each response type by adding (or multiplying) attacker-controlled fields from the daemon response to a fixed struct size in unsigned int arithmetic. Three cases can overflow: KSMBD_EVENT_RPC_REQUEST: msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz; KSMBD_EVENT_SHARE_CONFIG_REQUEST: msg_sz = sizeof(struct ksmbd_share_config_response) + resp->payload_sz; KSMBD_EVENT_LOGIN_REQUEST_EXT: msg_sz = sizeof(struct ksmbd_login_response_ext) + resp->ngroups * sizeof(gid_t); resp->payload_sz is __u32 and resp->ngroups is __s32. Each addition can wrap in unsigned int; the multiplication by sizeof(gid_t) mixes signed and size_t, so a negative ngroups is converted to SIZE_MAX before the multiply. A wrapped value of msg_sz that happens to equal entry->msg_sz bypasses the size check on the next line, and downstream consumers (smb2pdu.c:6742 memcpy using rpc_resp->payload_sz, kmemdup in ksmbd_alloc_user using resp_ext->ngroups) then trust the unverified length. Use check_add_overflow() on the RPC_REQUEST and SHARE_CONFIG_REQUEST paths to detect integer overflow without constraining functional payload size; userspace ksmbd-tools grows NDR responses in 4096-byte chunks for calls like NetShareEnumAll, so a hard transport cap is unworkable on the response side. For LOGIN_REQUEST_EXT, reject resp->ngroups outside the signed [0, NGROUPS_MAX] range up front and report the error from ipc_validate_msg() so it fires at the IPC boundary; with that bound the subsequent multiplication and addition stay well below UINT_MAX. The now-redundant ngroups check and pr_err in ksmbd_alloc_user() are removed. This is the response-side analogue of aab98e2dbd64 ("ksmbd: fix integer overflows on 32 bit systems"), which hardened the request side. Fixes: 0626e6641f6b ("cifsd: add server handler for central processing and tranport layers") Fixes: a77e0e02af1c ("ksmbd: add support for supplementary groups") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-6 Assisted-by: Codex:gpt-5-4 Signed-off-by: Michael Bommarito Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/mgmt/user_config.c | 6 ------ fs/smb/server/transport_ipc.c | 16 +++++++++++++--- 2 files changed, 13 insertions(+), 9 deletions(-) --- a/fs/smb/server/mgmt/user_config.c +++ b/fs/smb/server/mgmt/user_config.c @@ -56,12 +56,6 @@ struct ksmbd_user *ksmbd_alloc_user(stru goto err_free; if (resp_ext) { - if (resp_ext->ngroups > NGROUPS_MAX) { - pr_err("ngroups(%u) from login response exceeds max groups(%d)\n", - resp_ext->ngroups, NGROUPS_MAX); - goto err_free; - } - user->sgid = kmemdup(resp_ext->____payload, resp_ext->ngroups * sizeof(gid_t), KSMBD_DEFAULT_GFP); --- a/fs/smb/server/transport_ipc.c +++ b/fs/smb/server/transport_ipc.c @@ -13,6 +13,7 @@ #include #include #include +#include #include "vfs_cache.h" #include "transport_ipc.h" @@ -497,7 +498,9 @@ static int ipc_validate_msg(struct ipc_m { struct ksmbd_rpc_command *resp = entry->response; - msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz; + if (check_add_overflow(sizeof(struct ksmbd_rpc_command), + resp->payload_sz, &msg_sz)) + return -EINVAL; break; } case KSMBD_EVENT_SPNEGO_AUTHEN_REQUEST: @@ -516,8 +519,9 @@ static int ipc_validate_msg(struct ipc_m if (resp->payload_sz < resp->veto_list_sz) return -EINVAL; - msg_sz = sizeof(struct ksmbd_share_config_response) + - resp->payload_sz; + if (check_add_overflow(sizeof(struct ksmbd_share_config_response), + resp->payload_sz, &msg_sz)) + return -EINVAL; } break; } @@ -526,6 +530,12 @@ static int ipc_validate_msg(struct ipc_m struct ksmbd_login_response_ext *resp = entry->response; if (resp->ngroups) { + if (resp->ngroups < 0 || + resp->ngroups > NGROUPS_MAX) { + pr_err("ngroups(%d) from login response exceeds max groups(%d)\n", + resp->ngroups, NGROUPS_MAX); + return -EINVAL; + } msg_sz = sizeof(struct ksmbd_login_response_ext) + resp->ngroups * sizeof(gid_t); }