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envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=148.163.156.1; envelope-from=nikhilks@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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @ibm.com) X-ZM-MESSAGEID: 1785920806208158500 Content-Type: text/plain; charset="utf-8" A guest-triggerable assertion crash (DoS) exists in pnv_phb4_config_write() and pnv_phb4_config_read(). When a guest performs an 8-byte access to PHB_CONFIG_DATA (offset 0x130), QEMU aborts because the switch(size) statement in the config accessors only handles 1, 2, and 4-byte accesses, hitting g_assert_not_reached() in the default case. Since guest input is untrusted, an invalid access size should not crash the host. Fix this by adding a size > 4 guard in pnv_phb4_reg_write() and pnv_phb4_reg_read() before the config accessor calls, and by replacing the g_assert_not_reached() in pnv_phb4_config_write() and pnv_phb4_config_read() with phb_error() to cover any other callers. Invalid reads now return ~0ull, maintaining PCI conventions. Fixes: 4f9924c4d4cf ("ppc/pnv: Add models for POWER9 PHB4 PCIe Host bridge") Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3591 Signed-off-by: Nikhil Kumar Singh --- hw/pci-host/pnv_phb4.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/hw/pci-host/pnv_phb4.c b/hw/pci-host/pnv_phb4.c index 705a5bcf07..02ca2f978c 100644 --- a/hw/pci-host/pnv_phb4.c +++ b/hw/pci-host/pnv_phb4.c @@ -84,7 +84,9 @@ static void pnv_phb4_config_write(PnvPHB4 *phb, unsigned = off, val =3D bswap32(val); break; default: - g_assert_not_reached(); + phb_error(phb, "invalid config write size %u at offset 0x%x\n", + size, off); + return; } pci_host_config_write_common(pdev, cfg_addr, limit, val, size); } @@ -119,7 +121,9 @@ static uint64_t pnv_phb4_config_read(PnvPHB4 *phb, unsi= gned off, case 4: return bswap32(val); default: - g_assert_not_reached(); + phb_error(phb, "invalid config read size %u at offset 0x%x\n", + size, off); + return ~0ull; } } =20 @@ -507,6 +511,11 @@ static void pnv_phb4_reg_write(void *opaque, hwaddr of= f, uint64_t val, =20 /* Special case outbound configuration data */ if ((off & 0xfffc) =3D=3D PHB_CONFIG_DATA) { + if (size > 4) { + phb_error(phb, "invalid config write size %u at 0x%"PRIx64"\n", + size, off); + return; + } pnv_phb4_config_write(phb, off & 0x3, size, val); return; } @@ -644,6 +653,11 @@ static uint64_t pnv_phb4_reg_read(void *opaque, hwaddr= off, unsigned size) uint64_t val; =20 if ((off & 0xfffc) =3D=3D PHB_CONFIG_DATA) { + if (size > 4) { + phb_error(phb, "invalid config read size %u at 0x%"PRIx64"\n", + size, off); + return ~0ull; + } return pnv_phb4_config_read(phb, off & 0x3, size); } =20 --=20 2.54.0