/* * Line 6 Linux USB driver * * Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation, version 2. * */ /* PCM interface to POD series devices. */ #ifndef PCM_H #define PCM_H #include #include "driver.h" /* number of USB frames per URB The Line 6 Windows driver always transmits two frames per packet, but the Linux driver performs significantly better (i.e., lower latency) with only one frame per packet. */ #define LINE6_ISO_PACKETS 1 /* in a "full speed" device (such as the PODxt Pro) this means 1ms, * for "high speed" it's 1/8ms */ #define LINE6_ISO_INTERVAL 1 #define LINE6_IMPULSE_DEFAULT_PERIOD 100 /* Get substream from Line 6 PCM data structure */ #define get_substream(line6pcm, stream) \ (line6pcm->pcm->streams[stream].substream) /* PCM mode bits. There are several features of the Line 6 USB driver which require PCM data to be exchanged with the device: *) PCM playback and capture via ALSA *) software monitoring (for devices without hardware monitoring) *) optional impulse response measurement However, from the device's point of view, there is just a single capture and playback stream, which must be shared between these subsystems. It is therefore necessary to maintain the state of the subsystems with respect to PCM usage. We define two bit flags, "opened" and "running", for each playback or capture stream. Both can contain the bit flag corresponding to LINE6_STREAM_* type, LINE6_STREAM_PCM = ALSA PCM playback or capture LINE6_STREAM_MONITOR = software monitoring IMPULSE = optional impulse response measurement The opened flag indicates whether the buffer is allocated while the running flag indicates whether the stream is running. For monitor or impulse operations, the driver needs to call line6_pcm_acquire() or line6_pcm_release() with the appropriate LINE6_STREAM_* flag. */ /* stream types */ enum { LINE6_STREAM_PCM, LINE6_STREAM_MONITOR, LINE6_STREAM_IMPULSE, LINE6_STREAM_CAPTURE_HELPER, }; /* misc bit flags for PCM operation */ enum { LINE6_FLAG_PAUSE_PLAYBACK, LINE6_FLAG_PREPARED, }; struct line6_pcm_properties { struct snd_pcm_hardware playback_hw, capture_hw; struct snd_pcm_hw_constraint_ratdens rates; int bytes_per_channel; }; struct line6_pcm_stream { /* allocated URBs */ struct urb **urbs; /* Temporary buffer; * Since the packet size is not known in advance, this buffer is * large enough to store maximum size packets. */ unsigned char *buffer; /* Free frame position in the buffer. */ snd_pcm_uframes_t pos; /* Count processed bytes; * This is modulo period size (to determine when a period is finished). */ unsigned bytes; /* Counter to create desired sample rate */ unsigned count; /* period size in bytes */ unsigned period; /* Processed frame position in the buffer; * The contents of the ring buffer have been consumed by the USB * subsystem (i.e., sent to the USB device) up to this position. */ snd_pcm_uframes_t pos_done; /* Bit mask of active URBs */ unsigned long active_urbs; /* Bit mask of URBs currently being unlinked */ unsigned long unlink_urbs; /* Spin lock to protect updates of the buffer positions (not contents) */ spinlock_t lock; /* Bit flags for operational stream types */ unsigned long opened; /* Bit flags for running stream types */ unsigned long running; int last_frame; }; struct snd_line6_pcm { /* Pointer back to the Line 6 driver data structure */ struct usb_line6 *line6; /* Properties. */ struct line6_pcm_properties *properties; /* ALSA pcm stream */ struct snd_pcm *pcm; /* protection to state changes of in/out streams */ struct mutex state_mutex; /* Capture and playback streams */ struct line6_pcm_stream in; struct line6_pcm_stream out; /* Previously captured frame (for software monitoring) */ unsigned char *prev_fbuf; /* Size of previously captured frame (for software monitoring/sync) */ int prev_fsize; /* Maximum size of USB packet */ int max_packet_size_in; int max_packet_size_out; /* PCM playback volume (left and right) */ int volume_playback[2]; /* PCM monitor volume */ int volume_monitor; /* Volume of impulse response test signal (if zero, test is disabled) */ int impulse_volume; /* Period of impulse response test signal */ int impulse_period; /* Counter for impulse response test signal */ int impulse_count; /* Several status bits (see LINE6_FLAG_*) */ unsigned long flags; }; extern int line6_init_pcm(struct usb_line6 *line6, struct line6_pcm_properties *properties); extern int snd_line6_trigger(struct snd_pcm_substream *substream, int cmd); extern int snd_line6_prepare(struct snd_pcm_substream *substream); extern int snd_line6_hw_params(struct snd_pcm_substream *substream, struct snd_pcm_hw_params *hw_params); extern int snd_line6_hw_free(struct snd_pcm_substream *substream); extern snd_pcm_uframes_t snd_line6_pointer(struct snd_pcm_substream *substream); extern void line6_pcm_disconnect(struct snd_line6_pcm *line6pcm); extern int line6_pcm_acquire(struct snd_line6_pcm *line6pcm, int type, bool start); extern void line6_pcm_release(struct snd_line6_pcm *line6pcm, int type); #endif .git/patch/drivers/usb/misc?id=191e885a2e130e639bb0c8ee350d7047294f2ce6'>patch) tree9bf9f9b4971df55a46e0a6750d3f6cd37bf1d9f0 /drivers/usb/misc parent49def1853334396f948dcb4cedb9347abb318df5 (diff)
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>
Diffstat (limited to 'drivers/usb/misc')