[BUG] sound/usb: out-of-bounds in usb6fire_pcm_in_urb_handler()

[co]

This is a bug report, not a patch submission.

We found a bug reachable in:

    path    sound/usb/6fire
    crash   out-of-bounds in usb6fire_pcm_in_urb_handler()
    commit  2f1baf1fc892 ("Merge tag 'trace-v7.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace")

Config, environment, the sanitizer report and a C reproducer follow.

== Notes ===============================================================
    If you fix this bug, this tag credits the report and lets us
    close it on our side:

Reported-by: co+855929c2df672879@xxxxxxx

    Everything in this mail is validated by the reproducer below.

    We also hold an unreviewed LLM-generated analysis and candidate
    patch. The same reproducer panics the unpatched kernel and runs
    clean with that patch applied. Use it as a starting point, or ignore
    it and write your own:

        patch.diff  https://bugs.sh/b/855929c2df672879/patch.diff
        report.md   https://bugs.sh/b/855929c2df672879/report.md

    Happy to test patches. Complaints and suggestions about our work
    are welcome at:

        cedalion@xxxxxxx

== Environment =========================================================
    Reproduced on  2f1baf1fc892 ("Merge tag 'trace-v7.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace")
    VM setup       https://bugs.sh/b/855929c2df672879/run.sh
    config         https://bugs.sh/b/855929c2df672879/config.gz
    poc            https://bugs.sh/b/855929c2df672879/repro.c

== Sanitizer Report ====================================================
BUG: KASAN: out-of-bounds in usb6fire_pcm_in_urb_handler (sound/usb/6fire/pcm.c:338 (discriminator 3))
Write of size 18446744073709551456 at addr ffff888029af8000 by task vhci_rx/5013
Call Trace:
dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
print_report (mm/kasan/report.c:378 mm/kasan/report.c:482)
kasan_report (mm/kasan/report.c:595)
kasan_check_range (mm/kasan/generic.c:186 mm/kasan/generic.c:200)
__asan_memset (mm/kasan/shadow.c:84 (discriminator 1))
usb6fire_pcm_in_urb_handler (sound/usb/6fire/pcm.c:338 (discriminator 3))
__usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1657)
usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1741)
vhci_rx_loop (drivers/usb/usbip/vhci_rx.c:107 (discriminator 1) drivers/usb/usbip/vhci_rx.c:242 (discriminator 1) drivers/usb/usbip/vhci_rx.c:265 (discriminator 1))
kthread (kernel/kthread.c:436)
ret_from_fork (arch/x86/kernel/process.c:158)
ret_from_fork_asm (arch/x86/entry/entry_64.S:245)
The buggy address belongs to the object at ffff888029af8000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 0 bytes inside of
4832-byte region [ffff888029af8000, ffff888029af92e0)
Kernel panic - not syncing: KASAN: panic_on_warn set ...


---
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