kernel/drivers/usb/class/cdc-wdm.c, branch linux-rolling-stable

usb: class: cdc-wdm: fix reordering issue in read code path

2026-03-19T15:15:05Z

commit 8df672bfe3ec2268c2636584202755898e547173 upstream. Quoting the bug report: Due to compiler optimization or CPU out-of-order execution, the desc->length update can be reordered before the memmove. If this happens, wdm_read() can see the new length and call copy_to_user() on uninitialized memory. This also violates LKMM data race rules [1]. Fix it by using WRITE_ONCE and memory barriers. Fixes: afba937e540c9 ("USB: CDC WDM driver") Cc: stable Signed-off-by: Oliver Neukum Closes: https://lore.kernel.org/linux-usb/CALbr=LbrUZn_cfp7CfR-7Z5wDTHF96qeuM=3fO2m-q4cDrnC4A@mail.gmail.com/ Reported-by: Gui-Dong Han Reviewed-by: Gui-Dong Han Link: https://patch.msgid.link/20260304130116.1721682-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman

Merge 6.15-rc4 into usb-next

2025-04-28T08:32:58Z

We need the USB fixes in here as well, and this resolves the following merge conflicts that were reported in linux-next: drivers/usb/chipidea/ci_hdrc_imx.c drivers/usb/host/xhci.h Reported-by: Stephen Rothwell Signed-off-by: Greg Kroah-Hartman

USB: wdm: add annotation

2025-04-11T14:27:34Z

This is not understandable without a comment on endianness Fixes: afba937e540c9 ("USB: CDC WDM driver") Cc: stable Signed-off-by: Oliver Neukum Link: https://lore.kernel.org/r/20250401084749.175246-5-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman

USB: wdm: wdm_wwan_port_tx_complete mutex in atomic context

2025-04-11T14:27:32Z

wdm_wwan_port_tx_complete is called from a completion handler with irqs disabled and possible in IRQ context usb_autopm_put_interface can take a mutex. Hence usb_autopm_put_interface_async must be used. Fixes: cac6fb015f71 ("usb: class: cdc-wdm: WWAN framework integration") Cc: stable Signed-off-by: Oliver Neukum Link: https://lore.kernel.org/r/20250401084749.175246-4-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman

USB: wdm: close race between wdm_open and wdm_wwan_port_stop

2025-04-11T14:27:28Z

Clearing WDM_WWAN_IN_USE must be the last action or we can open a chardev whose URBs are still poisoned Fixes: cac6fb015f71 ("usb: class: cdc-wdm: WWAN framework integration") Cc: stable Signed-off-by: Oliver Neukum Link: https://lore.kernel.org/r/20250401084749.175246-3-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman

USB: wdm: handle IO errors in wdm_wwan_port_start

2025-04-11T14:27:25Z

In case submitting the URB fails we must undo what we've done so far. Fixes: cac6fb015f71 ("usb: class: cdc-wdm: WWAN framework integration") Cc: stable Signed-off-by: Oliver Neukum Link: https://lore.kernel.org/r/20250401084749.175246-2-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman

usb: cdc-wdm: avoid setting WDM_READ for ZLP-s

2025-04-11T14:08:33Z

Don't set WDM_READ flag in wdm_in_callback() for ZLP-s, otherwise when userspace tries to poll for available data, it might - incorrectly - believe there is something available, and when it tries to non-blocking read it, it might get stuck in the read loop. For example this is what glib does for non-blocking read (briefly): 1. poll() 2. if poll returns with non-zero, starts a read data loop: a. loop on poll() (EINTR disabled) b. if revents was set, reads data I. if read returns with EINTR or EAGAIN, goto 2.a. II. otherwise return with data So if ZLP sets WDM_READ (#1), we expect data, and try to read it (#2). But as that was a ZLP, and we are doing non-blocking read, wdm_read() returns with EAGAIN (#2.b.I), so loop again, and try to read again (#2.a.). With glib, we might stuck in this loop forever, as EINTR is disabled (#2.a). Signed-off-by: Robert Hodaszi Acked-by: Oliver Neukum Link: https://lore.kernel.org/r/20250403144004.3889125-1-robert.hodaszi@digi.com Signed-off-by: Greg Kroah-Hartman

move asm/unaligned.h to linux/unaligned.h

2024-10-02T21:23:23Z

asm/unaligned.h is always an include of asm-generic/unaligned.h; might as well move that thing to linux/unaligned.h and include that - there's nothing arch-specific in that header. auto-generated by the following: for i in `git grep -l -w asm/unaligned.h`; do sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i done for i in `git grep -l -w asm-generic/unaligned.h`; do sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i done git mv include/asm-generic/unaligned.h include/linux/unaligned.h git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h

USB: class: cdc-wdm: Fix CPU lockup caused by excessive log messages

2024-06-14T06:47:59Z

The syzbot fuzzer found that the interrupt-URB completion callback in the cdc-wdm driver was taking too long, and the driver's immediate resubmission of interrupt URBs with -EPROTO status combined with the dummy-hcd emulation to cause a CPU lockup: cdc_wdm 1-1:1.0: nonzero urb status received: -71 cdc_wdm 1-1:1.0: wdm_int_callback - 0 bytes watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [syz-executor782:6625] CPU#0 Utilization every 4s during lockup: #1: 98% system, 0% softirq, 3% hardirq, 0% idle #2: 98% system, 0% softirq, 3% hardirq, 0% idle #3: 98% system, 0% softirq, 3% hardirq, 0% idle #4: 98% system, 0% softirq, 3% hardirq, 0% idle #5: 98% system, 1% softirq, 3% hardirq, 0% idle Modules linked in: irq event stamp: 73096 hardirqs last enabled at (73095): [] console_emit_next_record kernel/printk/printk.c:2935 [inline] hardirqs last enabled at (73095): [] console_flush_all+0x650/0xb74 kernel/printk/printk.c:2994 hardirqs last disabled at (73096): [] __el1_irq arch/arm64/kernel/entry-common.c:533 [inline] hardirqs last disabled at (73096): [] el1_interrupt+0x24/0x68 arch/arm64/kernel/entry-common.c:551 softirqs last enabled at (73048): [] softirq_handle_end kernel/softirq.c:400 [inline] softirqs last enabled at (73048): [] handle_softirqs+0xa60/0xc34 kernel/softirq.c:582 softirqs last disabled at (73043): [] __do_softirq+0x14/0x20 kernel/softirq.c:588 CPU: 0 PID: 6625 Comm: syz-executor782 Tainted: G W 6.10.0-rc2-syzkaller-g8867bbd4a056 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 Testing showed that the problem did not occur if the two error messages -- the first two lines above -- were removed; apparently adding material to the kernel log takes a surprisingly large amount of time. In any case, the best approach for preventing these lockups and to avoid spamming the log with thousands of error messages per second is to ratelimit the two dev_err() calls. Therefore we replace them with dev_err_ratelimited(). Signed-off-by: Alan Stern Suggested-by: Greg KH Reported-and-tested-by: syzbot+5f996b83575ef4058638@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-usb/00000000000073d54b061a6a1c65@google.com/ Reported-and-tested-by: syzbot+1b2abad17596ad03dcff@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-usb/000000000000f45085061aa9b37e@google.com/ Fixes: 9908a32e94de ("USB: remove err() macro from usb class drivers") Link: https://lore.kernel.org/linux-usb/40dfa45b-5f21-4eef-a8c1-51a2f320e267@rowland.harvard.edu/ Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/29855215-52f5-4385-b058-91f42c2bee18@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman

Revert "usb: cdc-wdm: close race between read and workqueue"

2024-04-18T14:33:28Z

This reverts commit 339f83612f3a569b194680768b22bf113c26a29d. It has been found to cause problems in a number of Chromebook devices, so revert the change until it can be brought back in a safe way. Link: https://lore.kernel.org/r/385a3519-b45d-48c5-a6fd-a3fdb6bec92f@chromium.org Reported-by:: Aleksander Morgado Fixes: 339f83612f3a ("usb: cdc-wdm: close race between read and workqueue") Cc: stable Cc: Oliver Neukum Cc: Bjørn Mork Signed-off-by: Greg Kroah-Hartman