From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 ECAF23A5436; Fri, 7 Aug 2026 15:25:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786116341; cv=none; b=S7sTVcnKVFdIHYbfEt8rD/kDxpeH4KLuM4T/FTEkWieBR68ka2/MbjNyPrubRp1m6MiA2FqBAYq0HtJngdM/fdhzQpRnHyN5K/jCA4JsWkRMR++J4+Okd0nkdfZ9OF3NNvno9veI+r5v+0CDjubgPZRQnCCYugTV85yN072kyDc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786116341; c=relaxed/simple; bh=JyEnNQRUFozciUI9KJkk0IyNOKv5BuOyh3wUWzzoQUg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RaN7KAE4TrZaKug+fE6DfIE5uBNz17spgFmwJmVlkuYq0oUcG7cEdm1t/3FCPwW0wLaggAdR8FXMW1NtypTeiTg8DbgbApvAeOJpeTMZfGautLhSXvvHH9slxrJGLSML69gvOHJmqNRLLosCI+zWqp9TbR7x5SWyugESGIC6AvQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jy8W9uNZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="jy8W9uNZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F45B1F000E9; Fri, 7 Aug 2026 15:25:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786116339; bh=GyrdpeclBA3gzjbIj2XQExKhviI8u/LzqwUhb0+BWzs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jy8W9uNZ4wGnz9o7mFr0DMqr9I0L2zFRICIVWcRXq25m3m4uyv6WuzrVAEaZkfsZU 0D8bBfzAyYRi39oqE8p6m6V2yJJ7+pcihf4ZE/c08w0Z/pERkWw2pyPW9RtoNJ74Eh 2cZ5lvMZagLrTgb5tfcvK5J6vE1VMnR7l9muxspg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, William Palacek , Alysa Liu , Alex Deucher Subject: [PATCH 6.6 196/261] drm/amdkfd: hold event_mutex while checkpointing CRIU events Date: Fri, 7 Aug 2026 16:39:13 +0200 Message-ID: <20260807143419.598148841@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260807143415.358597922@linuxfoundation.org> References: <20260807143415.358597922@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: William Palacek commit ff8bc5a68a9a70bdc38d61a72c7a49c56063f9d2 upstream. kfd_criu_checkpoint_events() counts the entries in p->event_idr via kfd_get_num_events(), allocates an array sized to that count, and then walks the same IDR to fill it. Neither the count nor the walk holds p->event_mutex. The CRIU checkpoint caller holds only p->mutex. Event create and destroy (kfd_event_create()/kfd_event_destroy()) take p->event_mutex and do not take p->mutex, so a second thread in the same process can insert or remove events between the count and the walk. If an event is inserted, the walk iterates more entries than were counted and writes past the end of the ev_privs allocation; if an event is removed, the walk dereferences an entry that is being freed. Hold p->event_mutex across the count and the walk so both observe a consistent view of p->event_idr. The lock is released before copy_to_user(), which only touches the local buffer. The caller already holds p->mutex and the create/destroy paths never take p->mutex, so the p->mutex -> p->event_mutex order is not inverted and no deadlock is introduced. Fixes: 40e8a766a761 ("drm/amdkfd: CRIU checkpoint and restore events") Signed-off-by: William Palacek Reviewed-by: Alysa Liu Signed-off-by: Alex Deucher (cherry picked from commit ff57e223ab105795b05d3ef3f3c35a5a441bcbaa) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/amd/amdkfd/kfd_events.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) --- a/drivers/gpu/drm/amd/amdkfd/kfd_events.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.c @@ -544,15 +544,27 @@ int kfd_criu_checkpoint_events(struct kf int ret = 0; struct kfd_event *ev; uint32_t ev_id; + uint32_t num_events; - uint32_t num_events = kfd_get_num_events(p); - - if (!num_events) + /* Serialize the count and the walk below against concurrent event + * create/destroy. Those paths take only p->event_mutex, not the + * p->mutex held by the CRIU checkpoint caller, so without this the + * event_idr can grow between kfd_get_num_events() and the loop and the + * walk writes past the ev_privs allocation. + */ + mutex_lock(&p->event_mutex); + + num_events = kfd_get_num_events(p); + if (!num_events) { + mutex_unlock(&p->event_mutex); return 0; + } ev_privs = kvzalloc(num_events * sizeof(*ev_privs), GFP_KERNEL); - if (!ev_privs) + if (!ev_privs) { + mutex_unlock(&p->event_mutex); return -ENOMEM; + } idr_for_each_entry(&p->event_idr, ev, ev_id) { @@ -593,6 +605,8 @@ int kfd_criu_checkpoint_events(struct kf i++; } + mutex_unlock(&p->event_mutex); + ret = copy_to_user(user_priv_data + *priv_data_offset, ev_privs, num_events * sizeof(*ev_privs)); if (ret) {