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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id u11sm369896pfk.100.2021.08.18.10.30.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Aug 2021 10:30:21 -0700 (PDT) From: Kees Cook To: Greg Kroah-Hartman Cc: Kees Cook , Arnd Bergmann , Al Cooper , Alan Stern , linux-usb@vger.kernel.org, Andy Shevchenko , Florian Fainelli , linux-kernel@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, linux-hardening@vger.kernel.org Subject: [PATCH v2 1/2] USB: EHCI: Add register array bounds to HCS ports Date: Wed, 18 Aug 2021 10:30:17 -0700 Message-Id: <20210818173018.2259231-2-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210818173018.2259231-1-keescook@chromium.org> References: <20210818173018.2259231-1-keescook@chromium.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=7220; h=from:subject; bh=PrqH4P4vgVZHKHE7nIvTnE+3btKaALDbLdB8dmZoNEI=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBhHUOpcMWD7KZ+H+r80r7RC5G00877NCfhWVaDpd7f 8ZI1FeeJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYR1DqQAKCRCJcvTf3G3AJpPeD/ 0ViHu9opQky3KDanpgGOzZIL18aR0Bx/Bm6XDM3MmyR4df8yDPbU9I0zXUNIaSyrdchhie0sr5y+88 4ysGTiwq0f+MKfVB6iWODt4BPVqjqovMTZAJjyVR/NRGwDEEuDtwm37f0/jAuYNaf6ticufZMaqDcW KmukSyx4WI0va1FFZR271UPZnbS/VIIWh+vCH8jv87CkFCWlPY2gtBGGQn3OYGn4gqt5kWKUMFe36g Zu8kPVke1d7c8q9VoXtixZn8hve/ft0rHQGl2MYsliukfAawnZH2vumDBuhYtaRpNpTPDXfftL4kyZ oTKwk4G+kM3xl8MR91QWmFV0683p1mQkZ5J9rUW5n9IwpJQ9gEptk1mfZd1jBc8NSSMaISAaVQUPsQ 2NM/vkA9V5+vT+3NoOEHus+Glx4mTD0INYbZcX0/IqYQk+WqrXk+8sDIivdKU499jdtRCPlW3g0d55 ucCLL+kuGVXr5eiUkTvaJ8mLHtVKfDtoc3RlWo7tmVgArqpQNXU7saK1TsH4ok89kSWZa2vQwbpMAv 00W223CGoy8rnNsfjHuJXuKPoiDQVu92rahjq+6GwZE7voYekWASEmfhrYsRMgwFJHn7pZkfKGYXOM vp5h4XTEsHJALXSxk2udy+IdC2sXaMwx0wruae+uipEFiXLkHx4TCUpWFvxQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org The original EHCI register struct used a trailing 0-element array for addressing the N_PORTS-many available registers. However, after commit a46af4ebf9ff ("USB: EHCI: define extension registers like normal ones") the 0-element array started to overlap the USBMODE extension register. To avoid future compile-time warnings about accessing indexes within a 0-element array, rearrange the struct to actually describe the expected layout (max 15 registers) with a union. All offsets remain the same, and bounds checking becomes possible on accesses to port_status and hostpc. There are no binary differences, and struct offsets continue to match. "pahole --hex -C ehci_regs" before: struct ehci_regs { u32 command; /* 0 0x4 */ u32 status; /* 0x4 0x4 */ u32 intr_enable; /* 0x8 0x4 */ u32 frame_index; /* 0xc 0x4 */ u32 segment; /* 0x10 0x4 */ u32 frame_list; /* 0x14 0x4 */ u32 async_next; /* 0x18 0x4 */ u32 reserved1[2]; /* 0x1c 0x8 */ u32 txfill_tuning; /* 0x24 0x4 */ u32 reserved2[6]; /* 0x28 0x18 */ /* --- cacheline 1 boundary (64 bytes) --- */ u32 configured_flag; /* 0x40 0x4 */ u32 port_status[0]; /* 0x44 0 */ u32 reserved3[9]; /* 0x44 0x24 */ u32 usbmode; /* 0x68 0x4 */ u32 reserved4[6]; /* 0x6c 0x18 */ /* --- cacheline 2 boundary (128 bytes) was 4 bytes ago --- */ u32 hostpc[0]; /* 0x84 0 */ u32 reserved5[17]; /* 0x84 0x44 */ /* --- cacheline 3 boundary (192 bytes) was 8 bytes ago --- */ u32 usbmode_ex; /* 0xc8 0x4 */ /* size: 204, cachelines: 4, members: 18 */ /* last cacheline: 12 bytes */ }; after: struct ehci_regs { u32 command; /* 0 0x4 */ u32 status; /* 0x4 0x4 */ u32 intr_enable; /* 0x8 0x4 */ u32 frame_index; /* 0xc 0x4 */ u32 segment; /* 0x10 0x4 */ u32 frame_list; /* 0x14 0x4 */ u32 async_next; /* 0x18 0x4 */ u32 reserved1[2]; /* 0x1c 0x8 */ u32 txfill_tuning; /* 0x24 0x4 */ u32 reserved2[6]; /* 0x28 0x18 */ /* --- cacheline 1 boundary (64 bytes) --- */ u32 configured_flag; /* 0x40 0x4 */ union { u32 port_status[15]; /* 0x44 0x3c */ struct { u32 reserved3[9]; /* 0x44 0x24 */ u32 usbmode; /* 0x68 0x4 */ }; /* 0x44 0x28 */ }; /* 0x44 0x3c */ /* --- cacheline 2 boundary (128 bytes) --- */ u32 reserved4; /* 0x80 0x4 */ u32 hostpc[15]; /* 0x84 0x3c */ /* --- cacheline 3 boundary (192 bytes) --- */ u32 reserved5[2]; /* 0xc0 0x8 */ u32 usbmode_ex; /* 0xc8 0x4 */ /* size: 204, cachelines: 4, members: 16 */ /* last cacheline: 12 bytes */ }; With this fixed, adding -Wzero-length-bounds to the build no longer produces several warnings like this: In file included from drivers/usb/host/ehci-hcd.c:306: drivers/usb/host/ehci-hub.c: In function 'ehci_port_handed_over': drivers/usb/host/ehci-hub.c:1194:8: warning: array subscript '' is outside the bounds of an interior zero-length array 'u32[0]' {aka 'unsigned int[]'} [-Wzero-length-bounds] 1194 | reg = &ehci->regs->port_status[portnum - 1]; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from drivers/usb/host/ehci.h:274, from drivers/usb/host/ehci-hcd.c:97: ./include/linux/usb/ehci_def.h:130:7: note: while referencing 'port_status' 130 | u32 port_status[0]; /* up to N_PORTS */ | ^~~~~~~~~~~ Cc: Greg Kroah-Hartman Cc: Arnd Bergmann Cc: Al Cooper Cc: Alan Stern Cc: linux-usb@vger.kernel.org Signed-off-by: Kees Cook --- include/linux/usb/ehci_def.h | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/include/linux/usb/ehci_def.h b/include/linux/usb/ehci_def.h index 78e006355557..dcbe2b068569 100644 --- a/include/linux/usb/ehci_def.h +++ b/include/linux/usb/ehci_def.h @@ -45,6 +45,7 @@ struct ehci_caps { #define HCS_PORTROUTED(p) ((p)&(1 << 7)) /* true: port routing */ #define HCS_PPC(p) ((p)&(1 << 4)) /* true: port power control */ #define HCS_N_PORTS(p) (((p)>>0)&0xf) /* bits 3:0, ports on HC */ +#define HCS_N_PORTS_MAX 15 /* N_PORTS valid 0x1-0xF */ u32 hcc_params; /* HCCPARAMS - offset 0x8 */ /* EHCI 1.1 addendum */ @@ -126,8 +127,9 @@ struct ehci_regs { u32 configured_flag; #define FLAG_CF (1<<0) /* true: we'll support "high speed" */ - /* PORTSC: offset 0x44 */ - u32 port_status[0]; /* up to N_PORTS */ + union { + /* PORTSC: offset 0x44 */ + u32 port_status[HCS_N_PORTS_MAX]; /* up to N_PORTS */ /* EHCI 1.1 addendum */ #define PORTSC_SUSPEND_STS_ACK 0 #define PORTSC_SUSPEND_STS_NYET 1 @@ -164,28 +166,28 @@ struct ehci_regs { #define PORT_CSC (1<<1) /* connect status change */ #define PORT_CONNECT (1<<0) /* device connected */ #define PORT_RWC_BITS (PORT_CSC | PORT_PEC | PORT_OCC) - - u32 reserved3[9]; - - /* USBMODE: offset 0x68 */ - u32 usbmode; /* USB Device mode */ + struct { + u32 reserved3[9]; + /* USBMODE: offset 0x68 */ + u32 usbmode; /* USB Device mode */ + }; #define USBMODE_SDIS (1<<3) /* Stream disable */ #define USBMODE_BE (1<<2) /* BE/LE endianness select */ #define USBMODE_CM_HC (3<<0) /* host controller mode */ #define USBMODE_CM_IDLE (0<<0) /* idle state */ - - u32 reserved4[6]; + }; + u32 reserved4; /* Moorestown has some non-standard registers, partially due to the fact that * its EHCI controller has both TT and LPM support. HOSTPCx are extensions to * PORTSCx */ /* HOSTPC: offset 0x84 */ - u32 hostpc[0]; /* HOSTPC extension */ + u32 hostpc[HCS_N_PORTS_MAX]; #define HOSTPC_PHCD (1<<22) /* Phy clock disable */ #define HOSTPC_PSPD (3<<25) /* Port speed detection */ - u32 reserved5[17]; + u32 reserved5[2]; /* USBMODE_EX: offset 0xc8 */ u32 usbmode_ex; /* USB Device mode extension */