Hi, Thanks for the bug report. Coincidentally, I face the same problem with my TC Electronic Desktop Konnekt 6, which reports one available port and two invalidated ports, and investigate its cause. I think the problem occurs just for the devices which have three or more ports. I sent a fix[1] just now by referring to your suggestions. Would you please evaluate the fix with your device? I'm sorry for your inconvenience. [1] [PATCH] firewire: core: fix invalid port index for parent device https://lore.kernel.org/lkml/20241025034137.99317-1-o-takashi@xxxxxxxxxxxxx/ Thanks Takashi Sakamoto On Thu, Oct 24, 2024 at 01:56:31PM +0000, Edmund Raile wrote: > Hello, > > I'd like to report a regression in firewire-ohci that results > in the kernel hardlocking when re-discovering a FireWire device. > > TI XIO2213B > RME FireFace 800 > > It will occur under three conditions: > * power-cycling the FireWire device > * un- and re-plugging the FireWire device > * suspending and then waking the PC > > Often it would also occur directly on boot in QEMU but I have not > yet observed this specific behavior on bare metal. > > Here is an excerpt from the stack trace (don't know whether it is > acceptable to send in full): > > kernel: ------------[ cut here ]------------ > kernel: refcount_t: addition on 0; use-after-free. > kernel: WARNING: CPU: 3 PID: 116 at lib/refcount.c:25 > refcount_warn_saturate (/build/linux/lib/refcount.c:25 (discriminator > 1)) > kernel: Workqueue: firewire_ohci bus_reset_work > kernel: RIP: 0010:refcount_warn_saturate > (/build/linux/lib/refcount.c:25 (discriminator 1)) > kernel: Call Trace: > kernel: <TASK> > kernel: ? refcount_warn_saturate (/build/linux/lib/refcount.c:25 > (discriminator 1)) > kernel: ? __warn.cold (/build/linux/kernel/panic.c:693) > kernel: ? refcount_warn_saturate (/build/linux/lib/refcount.c:25 > (discriminator 1)) > kernel: ? report_bug (/build/linux/lib/bug.c:180 > /build/linux/lib/bug.c:219) > kernel: ? handle_bug (/build/linux/arch/x86/kernel/traps.c:218) > kernel: ? exc_invalid_op (/build/linux/arch/x86/kernel/traps.c:260 > (discriminator 1)) > kernel: ? asm_exc_invalid_op > (/build/linux/./arch/x86/include/asm/idtentry.h:621) > kernel: ? refcount_warn_saturate (/build/linux/lib/refcount.c:25 > (discriminator 1)) > kernel: for_each_fw_node (/build/linux/./include/linux/refcount.h:190 > /build/linux/./include/linux/refcount.h:241 > /build/linux/./include/linux/refcount.h:258 > /build/linux/drivers/firewire/core.h:199 > /build/linux/drivers/firewire/core-topology.c:275) > kernel: ? __pfx_report_found_node (/build/linux/drivers/firewire/core- > topology.c:312) > kernel: fw_core_handle_bus_reset (/build/linux/drivers/firewire/core- > topology.c:399 (discriminator 1) /build/linux/drivers/firewire/core- > topology.c:504 (discriminator 1)) > kernel: bus_reset_work (/build/linux/drivers/firewire/ohci.c:2121) > kernel: process_one_work > (/build/linux/./arch/x86/include/asm/jump_label.h:27 > /build/linux/./include/linux/jump_label.h:207 > /build/linux/./include/trace/events/workqueue.h:110 > /build/linux/kernel/workqueue.c:3236) > kernel: worker_thread (/build/linux/kernel/workqueue.c:3306 > (discriminator 2) /build/linux/kernel/workqueue.c:3393 (discriminator > 2)) > kernel: ? __pfx_worker_thread (/build/linux/kernel/workqueue.c:3339) > kernel: kthread (/build/linux/kernel/kthread.c:389) > kernel: ? __pfx_kthread (/build/linux/kernel/kthread.c:342) > kernel: ret_from_fork (/build/linux/arch/x86/kernel/process.c:153) > kernel: ? __pfx_kthread (/build/linux/kernel/kthread.c:342) > kernel: ret_from_fork_asm (/build/linux/arch/x86/entry/entry_64.S:254) > kernel: </TASK> > > I have identified the commit via bisection: > 24b7f8e5cd656196a13077e160aec45ad89b58d9 > firewire: core: use helper functions for self ID sequence > > It was part of the following patch series: > firewire: add tracepoints events for self ID sequence > https://lore.kernel.org/all/20240605235155.116468-6-o-takashi@xxxxxxxxxxxxx/ > > #regzbot introduced: 24b7f8e5cd65 > > Since this was before v6.10-rc5 and stable 6.10.14 is EOL, > stable v6.11.5 and mainline are affected. > > Reversion appears to be non-trivial as it is part of a patch > series, other files have been altered as well and other commits > build on top of it. > > Call chain: > core-topology.c fw_core_handle_bus_reset() > -> core-topology.c for_each_fw_node(card, local_node, > report_found_node) > -> core.h fw_node_get(root) > -> refcount.h __refcount_inc(&node) > -> refcount.h __refcount_add(1, r, oldp); > -> refcount.h refcount_warn_saturate(r, REFCOUNT_ADD_UAF); > -> refcount.h REFCOUNT_WARN("addition on 0; use-after-free") > > Since local_node of fw_core_handle_bus_reset() is retrieved by > local_node = build_tree(card, self_ids, self_id_count); > build_tree() needs to be looked at, it was indeed altered by > 24b7f8e5cd65. > > After a hard 3 hour look traversing all used functions and comparing > against the original function (as of e404cacfc5ed), this caught my eye: > for (port_index = 0; port_index < total_port_count; > ++port_index) { > switch (port_status) { > case PHY_PACKET_SELF_ID_PORT_STATUS_PARENT: > node->color = i; > > In both for loops, "port_index" was replaced by "i" > "i" remains in use above: > for (i = 0, h = &stack; i < child_port_count; i++) > h = h->prev; > > While the original also used the less descriptive i in the loop > for (i = 0; i < port_count; i++) { > switch (get_port_type(sid, i)) { > case SELFID_PORT_PARENT: > node->color = i; > but reset it to 0 at the beginning of the loop. > > So the stray "i" in the for loop should be replaced with the loop > iterator "port_index" as it is meant to be synchronous with the > loop iterator (i.e. the port_index), no? > > diff --git a/drivers/firewire/core-topology.c b/drivers/firewire/core- > topology.c > index 8c10f47cc8fc..7fd91ba9c9c4 100644 > --- a/drivers/firewire/core-topology.c > +++ b/drivers/firewire/core-topology.c > @@ -207,7 +207,7 @@ static struct fw_node *build_tree(struct fw_card > *card, const u32 *sid, int self > // the node->ports array where the > parent node should be. Later, > // when we handle the parent node, we > fix up the reference. > ++parent_count; > - node->color = i; > + node->color = port_index; > break; > > What threw me off was discaridng node->color as it would be replaced > later anyways (can't be important!), or so I thought. > > Please tell me, is this line of reasoning correct or am I missing > something? > > Compiling 24b7f8e5cd65 and later mainline with the patch above > resulted in a kernel that didn't crash! > > In case my solution should turn out to be correct, I will gladly > submit the patch. > > Kind regards, > Edmund Raile.
