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b=ZebIJuR9EN0NJmNn6FawrGD7XQHVPKrHqIIgrVlAmsfXeo1TFgs11bZQLzcLjV6Nk1Wpf7 cGLIJizjyhLZzKUcR6akEmaDPHT1izqV5NHIwcqyyoBByxqct+hIH4ic3Wf+vgNG36D02l jklpvy4I2ihTuJ2R4jVeXYh0sXz38D4= X-MC-Unique: jzfuBiPYNAmKQ5DWOEd_DQ-1 From: P J P To: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Subject: [PATCH v2] hw/ide: check null block before _cancel_dma_sync Date: Fri, 4 Sep 2020 00:01:38 +0530 Message-Id: <20200903183138.2161977-1-ppandit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ppandit@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=205.139.110.120; envelope-from=ppandit@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/03 01:58:20 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: John Snow , Ruhr-University , QEMU Developers , qemu-block@nongnu.org, Prasad J Pandit Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" From: Prasad J Pandit When cancelling an i/o operation via ide_cancel_dma_sync(), a block pointer may be null. Add check to avoid null pointer dereference. -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=3D%2Fide_nullp= tr1 =3D=3D1803100=3D=3DHint: address points to the zero page. #0 blk_bs ../block/block-backend.c:714 #1 blk_drain ../block/block-backend.c:1715 #2 ide_cancel_dma_sync ../hw/ide/core.c:723 #3 bmdma_cmd_writeb ../hw/ide/pci.c:298 #4 bmdma_write ../hw/ide/piix.c:75 #5 memory_region_write_accessor ../softmmu/memory.c:483 #6 access_with_adjusted_size ../softmmu/memory.c:544 #7 memory_region_dispatch_write ../softmmu/memory.c:1465 #8 flatview_write_continue ../exec.c:3176 ... Reported-by: Ruhr-University Signed-off-by: Prasad J Pandit --- hw/ide/core.c | 1 + hw/ide/pci.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-) Update v2: use an assert() call -> https://lists.nongnu.org/archive/html/qemu-devel/2020-08/msg08336.html diff --git a/hw/ide/core.c b/hw/ide/core.c index f76f7e5234..8105187f49 100644 --- a/hw/ide/core.c +++ b/hw/ide/core.c @@ -718,6 +718,7 @@ void ide_cancel_dma_sync(IDEState *s) * whole DMA operation will be submitted to disk with a single * aio operation with preadv/pwritev. */ + assert(s->blk); if (s->bus->dma->aiocb) { trace_ide_cancel_dma_sync_remaining(); blk_drain(s->blk); diff --git a/hw/ide/pci.c b/hw/ide/pci.c index b50091b615..b47e675456 100644 --- a/hw/ide/pci.c +++ b/hw/ide/pci.c @@ -295,7 +295,10 @@ void bmdma_cmd_writeb(BMDMAState *bm, uint32_t val) /* Ignore writes to SSBM if it keeps the old value */ if ((val & BM_CMD_START) !=3D (bm->cmd & BM_CMD_START)) { if (!(val & BM_CMD_START)) { - ide_cancel_dma_sync(idebus_active_if(bm->bus)); + IDEState *s =3D idebus_active_if(bm->bus); + if (s->blk) { + ide_cancel_dma_sync(s); + } bm->status &=3D ~BM_STATUS_DMAING; } else { bm->cur_addr =3D bm->addr; --=20 2.26.2