[SeaBIOS] hw/usb-msc.c: Branch condition evaluates to a garbage value

Mon, 29 Aug 2016 10:06:59 -0700 

Dear SeaBIOS developers,
Building the attached configuration with GCC 5.3.0 and the static analyzer scan-build shipped with Clang 3.8, the following error is reported in `src/hw/usb-msc.c` in line 110.
The static analyzer seems to think that the struct member is not initialized. But I guess it’s done in the line below, and therefore a false positive? 

```
ret = usb_msc_send(udrive_gf, USB_DIR_IN
                       , MAKE_FLATPTR(GET_SEG(SS), &csw), sizeof(csw));
```


Thanks,

Paul
Title: src/hw/usb-msc.c

Bug Summary

File:src/hw/usb-msc.c
Location:line 110, column 9
Description:Branch condition evaluates to a garbage value

Annotated Source Code

1// Code for handling USB Mass Storage Controller devices.
2//
3// Copyright (C) 2010 Kevin O'Connor <[email protected]>
4//
5// This file may be distributed under the terms of the GNU LGPLv3 license.
6
7#include "biosvar.h" // GET_GLOBALFLAT
8#include "block.h" // DTYPE_USB
9#include "blockcmd.h" // cdb_read
10#include "config.h" // CONFIG_USB_MSC
11#include "malloc.h" // free
12#include "output.h" // dprintf
13#include "std/disk.h" // DISK_RET_SUCCESS
14#include "string.h" // memset
15#include "usb.h" // struct usb_s
16#include "usb-msc.h" // usb_msc_setup
17#include "util.h" // bootprio_find_usb
18
19struct usbdrive_s {
20 struct drive_s drive;
21 struct usb_pipe *bulkin, *bulkout;
22 int lun;
23};
24
25
26/****************************************************************
27 * Bulk-only drive command processing
28 ****************************************************************/
29
30#define USB_CDB_SIZE12 12
31
32#define CBW_SIGNATURE0x43425355 0x43425355 // USBC
33
34struct cbw_s {
35 u32 dCBWSignature;
36 u32 dCBWTag;
37 u32 dCBWDataTransferLength;
38 u8 bmCBWFlags;
39 u8 bCBWLUN;
40 u8 bCBWCBLength;
41 u8 CBWCB[16];
42} PACKED__attribute__((packed));
43
44#define CSW_SIGNATURE0x53425355 0x53425355 // USBS
45
46struct csw_s {
47 u32 dCSWSignature;
48 u32 dCSWTag;
49 u32 dCSWDataResidue;
50 u8 bCSWStatus;
51} PACKED__attribute__((packed));
52
53static int
54usb_msc_send(struct usbdrive_s *udrive_gf, int dir, void *buf, u32 bytes)
55{
56 struct usb_pipe *pipe;
57 if (dir == USB_DIR_OUT0)
58 pipe = GET_GLOBALFLAT(udrive_gf->bulkout)(*(typeof(&(*(&(udrive_gf->bulkout)))))((void*)&
(*(&(udrive_gf->bulkout))) + get_global_offset()));
59 else
60 pipe = GET_GLOBALFLAT(udrive_gf->bulkin)(*(typeof(&(*(&(udrive_gf->bulkin)))))((void*)&
(*(&(udrive_gf->bulkin))) + get_global_offset()));
61 return usb_send_bulk(pipe, dir, buf, bytes);
62}
63
64// Low-level usb command transmit function.
65int
66usb_process_op(struct disk_op_s *op)
67{
68 if (!CONFIG_USB_MSC1)
1
Taking false branch
→
69 return 0;
70
71 dprintf(16, "usb_cmd_data id=%p write=%d count=%d buf=%p\n"do { if (8 && (16) <= 8) __dprintf(("usb_cmd_data id=%p write=%d count=%d buf=%p\n"
) , op->drive_gf, 0, op->count, op->buf_fl ); } while
(0)
72 , op->drive_gf, 0, op->count, op->buf_fl)do { if (8 && (16) <= 8) __dprintf(("usb_cmd_data id=%p write=%d count=%d buf=%p\n"
) , op->drive_gf, 0, op->count, op->buf_fl ); } while
(0);
73 struct usbdrive_s *udrive_gf = container_of(({ const typeof( ((struct usbdrive_s *)0)->drive ) *__mptr
= (op->drive_gf); (struct usbdrive_s *)( (char *)__mptr -
((size_t) &((struct usbdrive_s *)0)->drive) );})
74 op->drive_gf, struct usbdrive_s, drive)({ const typeof( ((struct usbdrive_s *)0)->drive ) *__mptr
= (op->drive_gf); (struct usbdrive_s *)( (char *)__mptr -
((size_t) &((struct usbdrive_s *)0)->drive) );});
75
76 // Setup command block wrapper.
77 struct cbw_s cbw;
78 memset(&cbw, 0, sizeof(cbw));
79 int blocksize = scsi_fill_cmd(op, cbw.CBWCB, USB_CDB_SIZE12);
80 if (blocksize < 0)
2
←
Assuming 'blocksize' is >= 0
→
3
←
Taking false branch
→
81 return default_process_op(op);
82 u32 bytes = blocksize * op->count;
83 cbw.dCBWSignature = CBW_SIGNATURE0x43425355;
84 cbw.dCBWTag = 999; // XXX
85 cbw.dCBWDataTransferLength = bytes;
86 cbw.bmCBWFlags = scsi_is_read(op) ? USB_DIR_IN0x80 : USB_DIR_OUT0;
4
←
'?' condition is false
→
87 cbw.bCBWLUN = GET_GLOBALFLAT(udrive_gf->lun)(*(typeof(&(*(&(udrive_gf->lun)))))((void*)&(*
(&(udrive_gf->lun))) + get_global_offset()));
88 cbw.bCBWCBLength = USB_CDB_SIZE12;
89
90 // Transfer cbw to device.
91 int ret = usb_msc_send(udrive_gf, USB_DIR_OUT0
92 , MAKE_FLATPTR(GET_SEG(SS), &cbw)((void*)(((u32)(0)<<4)+(u32)(&cbw))), sizeof(cbw));
93 if (ret)
5
←
Assuming 'ret' is 0
→
6
←
Taking false branch
→
94 goto fail;
95
96 // Transfer data to/from device.
97 if (bytes) {
7
←
Assuming 'bytes' is 0
→
8
←
Taking false branch
→
98 ret = usb_msc_send(udrive_gf, cbw.bmCBWFlags, op->buf_fl, bytes);
99 if (ret)
100 goto fail;
101 }
102
103 // Transfer csw info.
104 struct csw_s csw;
105 ret = usb_msc_send(udrive_gf, USB_DIR_IN0x80
106 , MAKE_FLATPTR(GET_SEG(SS), &csw)((void*)(((u32)(0)<<4)+(u32)(&csw))), sizeof(csw));
107 if (ret)
9
←
Assuming 'ret' is 0
→
10
←
Taking false branch
→
108 goto fail;
109
110 if (!csw.bCSWStatus)
11
←
Branch condition evaluates to a garbage value
111 return DISK_RET_SUCCESS0x00;
112 if (csw.bCSWStatus == 2)
113 goto fail;
114
115 if (blocksize)
116 op->count -= csw.dCSWDataResidue / blocksize;
117 return DISK_RET_EBADTRACK0x0c;
118
119fail:
120 // XXX - reset connection
121 dprintf(1, "USB transmission failed\n")do { if (8 && (1) <= 8) __dprintf(("USB transmission failed\n"
) ); } while (0);
122 return DISK_RET_EBADTRACK0x0c;
123}
124
125static int
126usb_msc_maxlun(struct usb_pipe *pipe)
127{
128 struct usb_ctrlrequest req;
129 req.bRequestType = USB_DIR_IN0x80 | USB_TYPE_CLASS(0x01 << 5) | USB_RECIP_INTERFACE0x01;
130 req.bRequest = 0xfe;
131 req.wValue = 0;
132 req.wIndex = 0;
133 req.wLength = 1;
134 unsigned char maxlun;
135 int ret = usb_send_default_control(pipe, &req, &maxlun);
136 if (ret)
137 return 0;
138 return maxlun;
139}
140
141static int
142usb_msc_lun_setup(struct usb_pipe *inpipe, struct usb_pipe *outpipe,
143 struct usbdevice_s *usbdev, int lun)
144{
145 // Allocate drive structure.
146 struct usbdrive_s *drive = malloc_fseg(sizeof(*drive));
147 if (!drive) {
148 warn_noalloc()__warn_noalloc(148, __func__);
149 return -1;
150 }
151 memset(drive, 0, sizeof(*drive));
152 if (usb_32bit_pipe(inpipe))
153 drive->drive.type = DTYPE_USB_320x71;
154 else
155 drive->drive.type = DTYPE_USB0x70;
156 drive->bulkin = inpipe;
157 drive->bulkout = outpipe;
158 drive->lun = lun;
159
160 int prio = bootprio_find_usb(usbdev, lun);
161 int ret = scsi_drive_setup(&drive->drive, "USB MSC", prio);
162 if (ret) {
163 dprintf(1, "Unable to configure USB MSC drive.\n")do { if (8 && (1) <= 8) __dprintf(("Unable to configure USB MSC drive.\n"
) ); } while (0);
164 free(drive);
165 return -1;
166 }
167 return 0;
168}
169
170/****************************************************************
171 * Setup
172 ****************************************************************/
173
174// Configure a usb msc device.
175int
176usb_msc_setup(struct usbdevice_s *usbdev)
177{
178 if (!CONFIG_USB_MSC1)
179 return -1;
180
181 // Verify right kind of device
182 struct usb_interface_descriptor *iface = usbdev->iface;
183 if ((iface->bInterfaceSubClass != US_SC_SCSI0x06 &&
184 iface->bInterfaceSubClass != US_SC_ATAPI_80700x05 &&
185 iface->bInterfaceSubClass != US_SC_ATAPI_80200x02)
186 || iface->bInterfaceProtocol != US_PR_BULK0x50) {
187 dprintf(1, "Unsupported MSC USB device (subclass=%02x proto=%02x)\n"do { if (8 && (1) <= 8) __dprintf(("Unsupported MSC USB device (subclass=%02x proto=%02x)\n"
) , iface->bInterfaceSubClass, iface->bInterfaceProtocol
); } while (0)
188 , iface->bInterfaceSubClass, iface->bInterfaceProtocol)do { if (8 && (1) <= 8) __dprintf(("Unsupported MSC USB device (subclass=%02x proto=%02x)\n"
) , iface->bInterfaceSubClass, iface->bInterfaceProtocol
); } while (0);
189 return -1;
190 }
191
192 // Find bulk in and bulk out endpoints.
193 struct usb_pipe *inpipe = NULL((void*)0), *outpipe = NULL((void*)0);
194 struct usb_endpoint_descriptor *indesc = usb_find_desc(
195 usbdev, USB_ENDPOINT_XFER_BULK2, USB_DIR_IN0x80);
196 struct usb_endpoint_descriptor *outdesc = usb_find_desc(
197 usbdev, USB_ENDPOINT_XFER_BULK2, USB_DIR_OUT0);
198 if (!indesc || !outdesc)
199 goto fail;
200 inpipe = usb_alloc_pipe(usbdev, indesc);
201 outpipe = usb_alloc_pipe(usbdev, outdesc);
202 if (!inpipe || !outpipe)
203 goto fail;
204
205 int maxlun = usb_msc_maxlun(usbdev->defpipe);
206 int lun, pipesused = 0;
207 for (lun = 0; lun < maxlun + 1; lun++) {
208 int ret = usb_msc_lun_setup(inpipe, outpipe, usbdev, lun);
209 if (!ret)
210 pipesused = 1;
211 }
212
213 if (!pipesused)
214 goto fail;
215
216 return 0;
217fail:
218 dprintf(1, "Unable to configure USB MSC device.\n")do { if (8 && (1) <= 8) __dprintf(("Unable to configure USB MSC device.\n"
) ); } while (0);
219 usb_free_pipe(usbdev, inpipe);
220 usb_free_pipe(usbdev, outpipe);
221 return -1;
222}
#
# Automatically generated file; DO NOT EDIT.
# SeaBIOS Configuration
#

#
# General Features
#
CONFIG_COREBOOT=y
# CONFIG_QEMU is not set
# CONFIG_CSM is not set
# CONFIG_QEMU_HARDWARE is not set
CONFIG_THREADS=y
CONFIG_RELOCATE_INIT=y
CONFIG_BOOTMENU=y
CONFIG_BOOTSPLASH=y
CONFIG_BOOTORDER=y
CONFIG_COREBOOT_FLASH=y
CONFIG_LZMA=y
CONFIG_CBFS_LOCATION=0
CONFIG_MULTIBOOT=y
CONFIG_ENTRY_EXTRASTACK=y
CONFIG_MALLOC_UPPERMEMORY=y
CONFIG_ROM_SIZE=0

#
# Hardware support
#
CONFIG_ATA=y
# CONFIG_ATA_DMA is not set
# CONFIG_ATA_PIO32 is not set
CONFIG_AHCI=y
CONFIG_SDCARD=y
CONFIG_MEGASAS=y
CONFIG_FLOPPY=y
CONFIG_FLASH_FLOPPY=y
CONFIG_PS2PORT=y
CONFIG_USB=y
CONFIG_USB_UHCI=y
CONFIG_USB_OHCI=y
CONFIG_USB_EHCI=y
CONFIG_USB_XHCI=y
CONFIG_USB_MSC=y
CONFIG_USB_UAS=y
CONFIG_USB_HUB=y
CONFIG_USB_KEYBOARD=y
CONFIG_USB_MOUSE=y
CONFIG_SERIAL=y
CONFIG_LPT=y
CONFIG_RTC_TIMER=y
CONFIG_HARDWARE_IRQ=y
CONFIG_PMTIMER=y
CONFIG_TSC_TIMER=y

#
# BIOS interfaces
#
CONFIG_DRIVES=y
CONFIG_CDROM_BOOT=y
CONFIG_CDROM_EMU=y
CONFIG_PCIBIOS=y
CONFIG_APMBIOS=y
CONFIG_PNPBIOS=y
CONFIG_OPTIONROMS=y
CONFIG_PMM=y
CONFIG_BOOT=y
CONFIG_KEYBOARD=y
CONFIG_KBD_CALL_INT15_4F=y
CONFIG_MOUSE=y
CONFIG_S3_RESUME=y
CONFIG_VGAHOOKS=y
# CONFIG_DISABLE_A20 is not set
CONFIG_TCGBIOS=y

#
# VGA ROM
#
CONFIG_NO_VGABIOS=y
# CONFIG_VGA_GEODEGX2 is not set
# CONFIG_VGA_GEODELX is not set
# CONFIG_VGA_COREBOOT is not set
# CONFIG_BUILD_VGABIOS is not set
CONFIG_VGA_EXTRA_STACK_SIZE=512

#
# Debugging
#
CONFIG_DEBUG_LEVEL=8
# CONFIG_DEBUG_SERIAL is not set
CONFIG_DEBUG_COREBOOT=y

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