Re: [PATCH net] e1000e: fix IRQ leak when request_irq() fails in e1000_request_msix()

[Simon Horman]

On Fri, Jun 26, 2026 at 04:39:16PM +0800, Jiayuan Chen wrote:
> An internal syzbot instance reported the warning below.
> 
> comedi (comedi_parport) lets userspace request_irq() an arbitrary IRQ
> number and can thus grab one of e1000e's MSI-X vectors. When
> e1000_request_msix() then fails partway through, it returned without
> freeing the vectors it had already requested; pci_disable_msix() later
> tears those descriptors down while their irqaction is still attached,
> leaking the /proc/irq entry.
> 
> Free the already requested IRQs on the error path.
> 
> genirq: Flags mismatch irq 28. 00200000 (eth1-tx-0) vs. 00200000 (comedi_parport)
> 
> remove_proc_entry: removing non-empty directory 'irq/27', leaking at least 'eth1-rx-0'
> WARNING: fs/proc/generic.c:742 at remove_proc_entry+0x436/0x560, CPU#3: ip/445
> Modules linked in:
> CPU: 3 UID: 0 PID: 445 Comm: ip Not tainted 7.1.0+ #284 PREEMPT
> RIP: 0010:remove_proc_entry (fs/proc/generic.c:742 (discriminator 4))
> PKRU: 55555554
> Call Trace:
> <TASK>
> unregister_irq_proc (kernel/irq/proc.c:406)
> free_desc (kernel/irq/irqdesc.c:482)
> irq_free_descs (kernel/irq/irqdesc.c:874 kernel/irq/irqdesc.c:865)
> irq_domain_free_irqs (kernel/irq/irqdomain.c:1917)
> msi_domain_free_locked.part.0 (kernel/irq/msi.c:1619 kernel/irq/msi.c:1645)
> msi_domain_free_irqs_all_locked (kernel/irq/msi.c:1632)
> pci_msi_teardown_msi_irqs (drivers/pci/msi/irqdomain.c:28)
> pci_free_msi_irqs (drivers/pci/msi/msi.c:925)
> pci_disable_msix (drivers/pci/msi/api.c:200 drivers/pci/msi/api.c:193)
> e1000_request_irq (drivers/net/ethernet/intel/e1000e/netdev.c:2028)
> e1000e_open (drivers/net/ethernet/intel/e1000e/netdev.c:4681)
> __dev_open (net/core/dev.c:1702)
> netif_change_flags (net/core/dev.c:9806)
> do_setlink.isra.0 (net/core/rtnetlink.c:3207 (discriminator 1))
> rtnetlink_rcv_msg (net/core/rtnetlink.c:7068)
> netlink_rcv_skb (net/netlink/af_netlink.c:2556)
> 
> Fixes: 4662e82b2cb4 ("e1000e: add support for new 82574L part")
> Signed-off-by: Jiayuan Chen <jiayuan.chen@xxxxxxxxx>
> Assisted-by: Claude:claude-opus-4-8

Reviewed-by: Simon Horman <horms@xxxxxxxxxx>