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Thu, 24 Sep 2026 13:50:07 +0000 (GMT) Received: from [9.47.158.153] (unknown [9.47.158.153]) by smtpav04.wdc07v.mail.ibm.com (Postfix) with ESMTP; Thu, 24 Sep 2026 13:50:07 +0000 (GMT) Message-ID: Date: Thu, 24 Sep 2026 09:50:06 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 06/10] hw/tpm: crb: Do not clear internal buffers when backend is busy To: marcandre.lureau@redhat.com Cc: qemu-devel@nongnu.org, armenon@redhat.com, marcandre.lureau@gmail.com References: <20260924012527.858527-1-stefanb@linux.ibm.com> <20260924012527.858527-7-stefanb@linux.ibm.com> <179023566486.1794827.4547558565411422420.b4-review@b4> Content-Language: en-US From: Stefan Berger In-Reply-To: <179023566486.1794827.4547558565411422420.b4-review@b4> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: LPl4aHAN38xSPkF99wDRmgrUoMh26PQ2 X-Authority-Analysis: v=2.4 cv=EOCTQFZC c=1 sm=1 tr=0 ts=6ab52a92 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=20KFwNOVAAAA:8 a=VnNF1IyMAAAA:8 a=2a8yVmhj0dxH-vjGAIsA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI0MDA1NiBTYWx0ZWRfX/BcyOTvKU9H+ K6orebW5wMit2wzgQ7+p5iH4UGRPOb9OTZIex0Cyg4NHgOdFBOCgxbHP0dgcmkpPnqhFpMFLNxC 3RPhOB6NJpE1XRJAMufEAd4vjWEXGvQ= X-Proofpoint-GUID: 4Cd3fmh5fEi287p1xv_e184eiy3BOoXK X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI0MDA1NiBTYWx0ZWRfX5SPRR80/dz+K wAq6/QTKNDQ1F+hp5a5UkknTyngOdE5b2+snifFxn2IX4MrdZK2NvlmHi0hMZVn4l8e7y2RfpZS BQRWwdLOL3UucmvXVjW8mtnBfYKPYZHgHKBKV8u+l0A47LUubfYia/dC765iYLzh8IpqFoXuBet wQYjCzdRhVheMs4t9p130tyGY3Zaor6QBY6axonKigaJEA8lLN9d+GxJw5ET5Wccg1IXXwjrfHE VjbMLpOhKdFaawqNF8E2uekTjqHI1GDos/ayeuBEZKmnzDleXDaaJu9J7XYQhnfii3szP49AnDc cxWsjYyAI17yO7EuQnURGUTYdJlsnfGTFrP2z1gsUQqu6XVIDBY5JeMOt90pHy8Vnz5rTq8RHR5 G5z2AODSOD61CLqA916Qbeh/MYY9uQxzU5M6FcqHGriRhTzStJm3Zru+GuLECxQ0883zGDasxjv yuQb7btL1gc1pDszqhA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-24_03,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 priorityscore=1501 clxscore=1015 spamscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609240056 Received-SPF: pass client-ip=148.163.156.1; envelope-from=stefanb@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 9/24/26 3:41 AM, marcandre.lureau@redhat.com wrote: >> While the backend (thread) is accessing the request and response buffers, >> do not clear those buffers upon a command cancellation. Still clear them >> in all other cases, though. >> >> Fixes: 29315d22b259 ("hw/tpm: Add internal buffer state for chunking") > > It's the following commit that makes use of it, but ok > > This may also lead to OOB read/crashes from malicious guest driver. For example g_byte_array_set_size(s->response_buffer, 0) does not seem to deallocate the memory in s->response_buffer just because it was set to size 0. Running the tests/qtest/tpm-crb-swtpm-test with this modification here requires me to disable asserts for expected responses but no crash actually occurs. @@ -254,6 +254,7 @@ static void tpm_crb_mmio_write(void *opaque, hwaddr addr, .out_len = s->response_buffer->len, }; tpm_backend_deliver_request(s->tpmbe, &s->cmd); + tpm_crb_clear_internal_buffers(s); } else if (val & CRB_START_NEXT_CHUNK) { if (!s->cap_chunk) { break; > >> Signed-off-by: Stefan Berger >> Message-ID: <20260924012527.858527-7-stefanb@linux.ibm.com> >> >> diff --git a/hw/tpm/tpm_crb.c b/hw/tpm/tpm_crb.c >> index 54fa2042b5a8..e5e33a3a2ff4 100644 >> --- a/hw/tpm/tpm_crb.c >> +++ b/hw/tpm/tpm_crb.c >> @@ -218,8 +218,9 @@ static void tpm_crb_mmio_write(void *opaque, hwaddr addr, >> if (val == CRB_CANCEL_INVOKE) { >> if (s->regs[R_CRB_CTRL_START] & CRB_START_INVOKE) { >> tpm_backend_cancel_cmd(s->tpmbe); >> + } else { >> + tpm_crb_clear_internal_buffers(s); >> } >> - tpm_crb_clear_internal_buffers(s); >> } >> break; >> case A_CRB_CTRL_START: > > Reviewed-by: Marc-André Lureau >