Subject: CVE-2021-47283: net:sfc: fix non-freed irq in legacy irq mode

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

net:sfc: fix non-freed irq in legacy irq mode

SFC driver can be configured via modparam to work using MSI-X, MSI or
legacy IRQ interrupts. In the last one, the interrupt was not properly
released on module remove.

It was not freed because the flag irqs_hooked was not set during
initialization in the case of using legacy IRQ.

Example of (trimmed) trace during module remove without this fix:

remove_proc_entry: removing non-empty directory 'irq/125', leaking at least '0000:3b:00.1'
WARNING: CPU: 39 PID: 3658 at fs/proc/generic.c:715 remove_proc_entry+0x15c/0x170
...trimmed...
Call Trace:
 unregister_irq_proc+0xe3/0x100
 free_desc+0x29/0x70
 irq_free_descs+0x47/0x70
 mp_unmap_irq+0x58/0x60
 acpi_unregister_gsi_ioapic+0x2a/0x40
 acpi_pci_irq_disable+0x78/0xb0
 pci_disable_device+0xd1/0x100
 efx_pci_remove+0xa1/0x1e0 [sfc]
 pci_device_remove+0x38/0xa0
 __device_release_driver+0x177/0x230
 driver_detach+0xcb/0x110
 bus_remove_driver+0x58/0xd0
 pci_unregister_driver+0x2a/0xb0
 efx_exit_module+0x24/0xf40 [sfc]
 __do_sys_delete_module.constprop.0+0x171/0x280
 ? exit_to_user_mode_prepare+0x83/0x1d0
 do_syscall_64+0x3d/0x80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f9f9385800b
...trimmed...

The Linux kernel CVE team has assigned CVE-2021-47283 to this issue.

Affected and fixed versions
===========================

	Fixed in 5.10.44 with commit 8d717c9135a3
	Fixed in 5.12.11 with commit 81c4d1d83f88
	Fixed in 5.13 with commit 8f03eeb6e0a0

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47283
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/sfc/nic.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/8d717c9135a3340ae62d1699484850bfb4112b0c
	https://git.kernel.org/stable/c/81c4d1d83f88e15b26f4522a35cba6ffd8c5dfdd
	https://git.kernel.org/stable/c/8f03eeb6e0a0a0b8d617ee0a4bce729e47130036