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Iglesias" , Darren Kenny , Bin Meng , Paolo Bonzini , Stefan Hajnoczi , "Michael S. Tsirkin" , Marcel Apfelbaum Subject: [PATCH v2 3/3] memory: fix bh-initiated dma-reentracy issues Date: Fri, 27 May 2022 12:19:37 -0400 Message-Id: <20220527161937.328754-4-alxndr@bu.edu> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20220527161937.328754-1-alxndr@bu.edu> References: <20220527161937.328754-1-alxndr@bu.edu> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CES-GSUITE_AUTH: bf3aNvsZpxl8 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=216.71.140.205; envelope-from=alxndr@bu.edu; helo=esa16.hc2706-39.iphmx.com X-Spam_score_int: 0 X-Spam_score: -0.1 X-Spam_bar: / X-Spam_report: (-0.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HK_RANDOM_ENVFROM=0.998, HK_RANDOM_FROM=0.998, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @bu.edu) X-ZM-MESSAGEID: 1653668540952100001 Content-Type: text/plain; charset="utf-8" This patch leverages the DeviceState engaged_in_io flag to prevent issues due to accesses similar to bh -> dma -> mmio. e.g. CVE-2021-3929 Signed-off-by: Alexander Bulekov --- include/hw/pci/pci.h | 13 +++++++++++-- softmmu/dma-helpers.c | 12 ++++++++++++ 2 files changed, 23 insertions(+), 2 deletions(-) diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h index 44dacfa224..ab1ad0f7a8 100644 --- a/include/hw/pci/pci.h +++ b/include/hw/pci/pci.h @@ -834,8 +834,17 @@ static inline MemTxResult pci_dma_rw(PCIDevice *dev, d= ma_addr_t addr, void *buf, dma_addr_t len, DMADirection dir, MemTxAttrs attrs) { - return dma_memory_rw(pci_get_address_space(dev), addr, buf, len, - dir, attrs); + bool prior_engaged_state; + MemTxResult result; + + prior_engaged_state =3D dev->qdev.engaged_in_io; + + dev->qdev.engaged_in_io =3D true; + result =3D dma_memory_rw(pci_get_address_space(dev), addr, buf, len, + dir, attrs); + dev->qdev.engaged_in_io =3D prior_engaged_state; + + return result; } =20 /** diff --git a/softmmu/dma-helpers.c b/softmmu/dma-helpers.c index 7820fec54c..7a4f1fb9b3 100644 --- a/softmmu/dma-helpers.c +++ b/softmmu/dma-helpers.c @@ -288,8 +288,16 @@ static MemTxResult dma_buf_rw(void *buf, dma_addr_t le= n, dma_addr_t *residual, uint8_t *ptr =3D buf; dma_addr_t xresidual; int sg_cur_index; + DeviceState *dev; + bool prior_engaged_state; MemTxResult res =3D MEMTX_OK; =20 + dev =3D sg->dev; + if (dev) { + prior_engaged_state =3D dev->engaged_in_io; + dev->engaged_in_io =3D true; + } + xresidual =3D sg->size; sg_cur_index =3D 0; len =3D MIN(len, xresidual); @@ -302,6 +310,10 @@ static MemTxResult dma_buf_rw(void *buf, dma_addr_t le= n, dma_addr_t *residual, xresidual -=3D xfer; } =20 + if (dev) { + dev->engaged_in_io =3D prior_engaged_state; + } + if (residual) { *residual =3D xresidual; } --=20 2.33.0