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b=jK2DhxfvbNa05wpjOzxp4SNiKk8o6lZmIGmoCFuEDZk7CxdbctF1iUwynOfwsCHxKIOJwb +r2xvwVWK+XoahOg603Uy13CNevYHmThKoiR21rBtS7Al4mZirbfzpav6v/AGfA1/pYt8a W/O/l0Hdq7ZXlpyvbm5jbqSr0bWHKKA= X-MC-Unique: NfuagYcmNJeL7l8d225rPw-1 From: P J P To: Gerd Hoffmann Subject: [PATCH v2] ati-vga: check mm_index before recursive call Date: Thu, 4 Jun 2020 00:25:22 +0530 Message-Id: <20200603185522.1173354-1-ppandit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 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=207.211.31.81; envelope-from=ppandit@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/03 01:12:11 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: Prasad J Pandit , Yi Ren , QEMU Developers , Ren Ding , Hanqing Zhao 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 While accessing VGA registers via ati_mm_read/write routines, a guest may set 's->regs.mm_index' such that it leads to infinite recursion. Check mm_index value to avoid it. Reported-by: Ren Ding Reported-by: Hanqing Zhao Reported-by: Yi Ren Signed-off-by: Prasad J Pandit Reviewed-by to cross check this. Suggested-by: BALATON Zoltan --- hw/display/ati.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Update v2: add check before recursive call -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00781.html diff --git a/hw/display/ati.c b/hw/display/ati.c index 065f197678..bda4a2d816 100644 --- a/hw/display/ati.c +++ b/hw/display/ati.c @@ -285,7 +285,7 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr, = unsigned int size) if (idx <=3D s->vga.vram_size - size) { val =3D ldn_le_p(s->vga.vram_ptr + idx, size); } - } else { + } else if (s->regs.mm_index > MM_DATA + 3) { val =3D ati_mm_read(s, s->regs.mm_index + addr - MM_DATA, size= ); } break; @@ -520,7 +520,7 @@ static void ati_mm_write(void *opaque, hwaddr addr, if (idx <=3D s->vga.vram_size - size) { stn_le_p(s->vga.vram_ptr + idx, size, data); } - } else { + } else if (s->regs.mm_index > MM_DATA + 3) { ati_mm_write(s, s->regs.mm_index + addr - MM_DATA, data, size); } break; --=20 2.26.2