/*
*
* Includes for cdc-acm.c
*
* Mainly take from usbnet's cdc-ether part
*
*/
/*
* CMSPAR, some architectures can't have space and mark parity.
*/
#ifndef CMSPAR
#define CMSPAR 0
#endif
/*
* Major and minor numbers.
*/
#define ACM_TTY_MAJOR 166
#define ACM_TTY_MINORS 256
/*
* Requests.
*/
#define USB_RT_ACM (USB_TYPE_CLASS | USB_RECIP_INTERFACE)
/*
* Output control lines.
*/
#define ACM_CTRL_DTR 0x01
#define ACM_CTRL_RTS 0x02
/*
* Input control lines and line errors.
*/
#define ACM_CTRL_DCD 0x01
#define ACM_CTRL_DSR 0x02
#define ACM_CTRL_BRK 0x04
#define ACM_CTRL_RI 0x08
#define ACM_CTRL_FRAMING 0x10
#define ACM_CTRL_PARITY 0x20
#define ACM_CTRL_OVERRUN 0x40
/*
* Internal driver structures.
*/
/*
* The only reason to have several buffers is to accommodate assumptions
* in line disciplines. They ask for empty space amount, receive our URB size,
* and proceed to issue several 1-character writes, assuming they will fit.
* The very first write takes a complete URB. Fortunately, this only happens
* when processing onlcr, so we only need 2 buffers. These values must be
* powers of 2.
*/
#define ACM_NW 16
#define ACM_NR 16
struct acm_wb {
unsigned char *buf;
dma_addr_t dmah;
int len;
int use;
struct urb *urb;
struct acm *instance;
};
struct acm_rb {
int size;
unsigned char *base;
dma_addr_t dma;
int index;
struct acm *instance;
};
struct acm {
struct usb_device *dev; /* the corresponding usb device */
struct usb_interface *control; /* control interface */
struct usb_interface *data; /* data interface */
unsigned in, out; /* i/o pipes */
struct tty_port port; /* our tty port data */
struct urb *ctrlurb; /* urbs */
u8 *ctrl_buffer; /* buffers of urbs */
dma_addr_t ctrl_dma; /* dma handles of buffers */
u8 *country_codes; /* country codes from device */
unsigned int country_code_size; /* size of this buffer */
unsigned int country_rel_date; /* release date of version */
struct acm_wb wb[ACM_NW];
unsigned long read_urbs_free;
struct urb *read_urbs[ACM_NR];
struct acm_rb read_buffers[ACM_NR];
struct acm_wb *putbuffer; /* for acm_tty_put_char() */
int rx_buflimit;
spinlock_t read_lock;
int write_used; /* number of non-empty write buffers */
int transmitting;
spinlock_t write_lock;
struct mutex mutex;
bool disconnected;
unsigned long flags;
# define EVENT_TTY_WAKEUP 0
# define EVENT_RX_STALL 1
struct usb_cdc_line_coding line; /* bits, stop, parity */
struct work_struct work; /* work queue entry for line discipline waking up */
unsigned int ctrlin; /* input control lines (DCD, DSR, RI, break, overruns) */
unsigned int ctrlout; /* output control lines (DTR, RTS) */
struct async_icount iocount; /* counters for control line changes */
struct async_icount oldcount; /* for comparison of counter */
wait_queue_head_t wioctl; /* for ioctl */
unsigned int writesize; /* max packet size for the output bulk endpoint */
unsigned int readsize,ctrlsize; /* buffer sizes for freeing */
unsigned int minor; /* acm minor number */
unsigned char clocal; /* termios CLOCAL */
unsigned int ctrl_caps; /* control capabilities from the class specific header */
unsigned int susp_count; /* number of suspended interfaces */
unsigned int combined_interfaces:1; /* control and data collapsed */
unsigned int throttled:1; /* actually throttled */
unsigned int throttle_req:1; /* throttle requested */
u8 bInterval;
struct usb_anchor delayed; /* writes queued for a device about to be woken */
unsigned long quirks;
};
#define CDC_DATA_INTERFACE_TYPE 0x0a
/* constants describing various quirks and errors */
#define NO_UNION_NORMAL BIT(0)
#define SINGLE_RX_URB BIT(1)
#define NO_CAP_LINE BIT(2)
#define NO_DATA_INTERFACE BIT(4)
#define IGNORE_DEVICE BIT(5)
#define QUIRK_CONTROL_LINE_STATE BIT(6)
#define CLEAR_HALT_CONDITIONS BIT(7)
#define SEND_ZERO_PACKET BIT(8)
bmit();'>
firmware: fix NULL pointer dereference in __fw_load_abort()
Since commit 5d47ec02c37ea6 ("firmware: Correct handling of
fw_state_wait() return value") fw_load_abort() could be called twice and
lead us to a kernel crash. This happens only when the firmware fallback
mechanism (regular or custom) is used. The fallback mechanism exposes a
sysfs interface for userspace to upload a file and notify the kernel
when the file is loaded and ready, or to cancel an upload by echo'ing -1
into on the loading file:
echo -n "-1" > /sys/$DEVPATH/loading
This will call fw_load_abort(). Some distributions actually have a udev
rule in place to *always* immediately cancel all firmware fallback
mechanism requests (Debian), they have:
$ cat /lib/udev/rules.d/50-firmware.rules
# stub for immediately telling the kernel that userspace firmware loading
# failed; necessary to avoid long timeouts with CONFIG_FW_LOADER_USER_HELPER=y
SUBSYSTEM=="firmware", ACTION=="add", ATTR{loading}="-1
Distributions with this udev rule would run into this crash only if the
fallback mechanism is used. Since most distributions disable by default
using the fallback mechanism (CONFIG_FW_LOADER_USER_HELPER_FALLBACK),
this would typicaly mean only 2 drivers which *require* the fallback
mechanism could typically incur a crash: drivers/firmware/dell_rbu.c and
the drivers/leds/leds-lp55xx-common.c driver. Distributions enabling
CONFIG_FW_LOADER_USER_HELPER_FALLBACK by default are obviously more
exposed to this crash.
The crash happens because after commit 5b029624948d ("firmware: do not
use fw_lock for fw_state protection") and subsequent fix commit
5d47ec02c37ea6 ("firmware: Correct handling of fw_state_wait() return
value") a race can happen between this cancelation and the firmware
fw_state_wait_timeout() being woken up after a state change with which
fw_load_abort() as that calls swake_up(). Upon error
fw_state_wait_timeout() will also again call fw_load_abort() and trigger
a null reference.
At first glance we could just fix this with a !buf check on
fw_load_abort() before accessing buf->fw_st, however there is a logical
issue in having a state machine used for the fallback mechanism and
preventing access from it once we abort as its inside the buf
(buf->fw_st).
The firmware_class.c code is setting the buf to NULL to annotate an
abort has occurred. Replace this mechanism by simply using the state
check instead. All the other code in place already uses similar checks
for aborting as well so no further changes are needed.
An oops can be reproduced with the new fw_fallback.sh fallback mechanism
cancellation test. Either cancelling the fallback mechanism or the
custom fallback mechanism triggers a crash.
mcgrof@piggy ~/linux-next/tools/testing/selftests/firmware
(git::20170111-fw-fixes)$ sudo ./fw_fallback.sh
./fw_fallback.sh: timeout works
./fw_fallback.sh: firmware comparison works
./fw_fallback.sh: fallback mechanism works
[ this then sits here when it is trying the cancellation test ]
Kernel log:
test_firmware: loading 'nope-test-firmware.bin'
misc test_firmware: Direct firmware load for nope-test-firmware.bin failed with error -2
misc test_firmware: Falling back to user helper
BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
IP: _request_firmware+0xa27/0xad0
PGD 0
Oops: 0000 [#1] SMP
Modules linked in: test_firmware(E) ... etc ...
CPU: 1 PID: 1396 Comm: fw_fallback.sh Tainted: G W E 4.10.0-rc3-next-20170111+ #30
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.1-0-g8891697-prebuilt.qemu-project.org 04/01/2014
task: ffff9740b27f4340 task.stack: ffffbb15c0bc8000
RIP: 0010:_request_firmware+0xa27/0xad0
RSP: 0018:ffffbb15c0bcbd10 EFLAGS: 00010246
RAX: 00000000fffffffe RBX: ffff9740afe5aa80 RCX: 0000000000000000
RDX: ffff9740b27f4340 RSI: 0000000000000283 RDI: 0000000000000000
RBP: ffffbb15c0bcbd90 R08: ffffbb15c0bcbcd8 R09: 0000000000000000
R10: 0000000894a0d4b1 R11: 000000000000008c R12: ffffffffc0312480
R13: 0000000000000005 R14: ffff9740b1c32400 R15: 00000000000003e8
FS: 00007f8604422700(0000) GS:ffff9740bfc80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000038 CR3: 000000012164c000 CR4: 00000000000006e0
Call Trace:
request_firmware+0x37/0x50
trigger_request_store+0x79/0xd0 [test_firmware]
dev_attr_store+0x18/0x30
sysfs_kf_write+0x37/0x40
kernfs_fop_write+0x110/0x1a0
__vfs_write+0x37/0x160
? _cond_resched+0x1a/0x50
vfs_write+0xb5/0x1a0
SyS_write+0x55/0xc0
? trace_do_page_fault+0x37/0xd0
entry_SYSCALL_64_fastpath+0x1e/0xad
RIP: 0033:0x7f8603f49620
RSP: 002b:00007fff6287b788 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055c307b110a0 RCX: 00007f8603f49620
RDX: 0000000000000016 RSI: 000055c3084d8a90 RDI: 0000000000000001
RBP: 0000000000000016 R08: 000000000000c0ff R09: 000055c3084d6336
R10: 000055c307b108b0 R11: 0000000000000246 R12: 000055c307b13c80
R13: 000055c3084d6320 R14: 0000000000000000 R15: 00007fff6287b950
Code: 9f 64 84 e8 9c 61 fe ff b8 f4 ff ff ff e9 6b f9 ff
ff 48 c7 c7 40 6b 8d 84 89 45 a8 e8 43 84 18 00 49 8b be 00 03 00 00 8b
45 a8 <83> 7f 38 02 74 08 e8 6e ec ff ff 8b 45 a8 49 c7 86 00 03 00 00
RIP: _request_firmware+0xa27/0xad0 RSP: ffffbb15c0bcbd10
CR2: 0000000000000038
---[ end trace 6d94ac339c133e6f ]---
Fixes: 5d47ec02c37e ("firmware: Correct handling of fw_state_wait() return value")
Reported-and-Tested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reported-and-Tested-by: Patrick Bruenn <p.bruenn@beckhoff.com>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
CC: <stable@vger.kernel.org> [3.10+]
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>