Subject: CVE-2021-47127: ice: track AF_XDP ZC enabled queues in bitmap

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

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

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

ice: track AF_XDP ZC enabled queues in bitmap

Commit c7a219048e45 ("ice: Remove xsk_buff_pool from VSI structure")
silently introduced a regression and broke the Tx side of AF_XDP in copy
mode. xsk_pool on ice_ring is set only based on the existence of the XDP
prog on the VSI which in turn picks ice_clean_tx_irq_zc to be executed.
That is not something that should happen for copy mode as it should use
the regular data path ice_clean_tx_irq.

This results in a following splat when xdpsock is run in txonly or l2fwd
scenarios in copy mode:

<snip>
[  106.050195] BUG: kernel NULL pointer dereference, address: 0000000000000030
[  106.057269] #PF: supervisor read access in kernel mode
[  106.062493] #PF: error_code(0x0000) - not-present page
[  106.067709] PGD 0 P4D 0
[  106.070293] Oops: 0000 [#1] PREEMPT SMP NOPTI
[  106.074721] CPU: 61 PID: 0 Comm: swapper/61 Not tainted 5.12.0-rc2+ #45
[  106.081436] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019
[  106.092027] RIP: 0010:xp_raw_get_dma+0x36/0x50
[  106.096551] Code: 74 14 48 b8 ff ff ff ff ff ff 00 00 48 21 f0 48 c1 ee 30 48 01 c6 48 8b 87 90 00 00 00 48 89 f2 81 e6 ff 0f 00 00 48 c1 ea 0c <48> 8b 04 d0 48 83 e0 fe 48 01 f0 c3 66 66 2e 0f 1f 84 00 00 00 00
[  106.115588] RSP: 0018:ffffc9000d694e50 EFLAGS: 00010206
[  106.120893] RAX: 0000000000000000 RBX: ffff88984b8c8a00 RCX: ffff889852581800
[  106.128137] RDX: 0000000000000006 RSI: 0000000000000000 RDI: ffff88984cd8b800
[  106.135383] RBP: ffff888123b50001 R08: ffff889896800000 R09: 0000000000000800
[  106.142628] R10: 0000000000000000 R11: ffffffff826060c0 R12: 00000000000000ff
[  106.149872] R13: 0000000000000000 R14: 0000000000000040 R15: ffff888123b50018
[  106.157117] FS:  0000000000000000(0000) GS:ffff8897e0f40000(0000) knlGS:0000000000000000
[  106.165332] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  106.171163] CR2: 0000000000000030 CR3: 000000000560a004 CR4: 00000000007706e0
[  106.178408] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  106.185653] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  106.192898] PKRU: 55555554
[  106.195653] Call Trace:
[  106.198143]  <IRQ>
[  106.200196]  ice_clean_tx_irq_zc+0x183/0x2a0 [ice]
[  106.205087]  ice_napi_poll+0x3e/0x590 [ice]
[  106.209356]  __napi_poll+0x2a/0x160
[  106.212911]  net_rx_action+0xd6/0x200
[  106.216634]  __do_softirq+0xbf/0x29b
[  106.220274]  irq_exit_rcu+0x88/0xc0
[  106.223819]  common_interrupt+0x7b/0xa0
[  106.227719]  </IRQ>
[  106.229857]  asm_common_interrupt+0x1e/0x40
</snip>

Fix this by introducing the bitmap of queues that are zero-copy enabled,
where each bit, corresponding to a queue id that xsk pool is being
configured on, will be set/cleared within ice_xsk_pool_{en,dis}able and
checked within ice_xsk_pool(). The latter is a function used for
deciding which napi poll routine is executed.
Idea is being taken from our other drivers such as i40e and ixgbe.

The Linux kernel CVE team has assigned CVE-2021-47127 to this issue.

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

	Issue introduced in 5.12 with commit c7a219048e45 and fixed in 5.12.10 with commit 1d34fa4fcf06
	Issue introduced in 5.12 with commit c7a219048e45 and fixed in 5.13 with commit e102db780e1c

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-2021-47127
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/intel/ice/ice.h
	drivers/net/ethernet/intel/ice/ice_lib.c
	drivers/net/ethernet/intel/ice/ice_xsk.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/1d34fa4fcf06649036ba0c97854fcf7a741ee18c
	https://git.kernel.org/stable/c/e102db780e1c14f10c70dafa7684af22a745b51d