xen/netback: don't call kfree_skb() with interrupts disabled

[ Upstream commit 74e7e1efdad45580cc3839f2a155174cf158f9b5 ]

It is not allowed to call kfree_skb() from hardware interrupt
context or with interrupts being disabled. So remove kfree_skb()
from the spin_lock_irqsave() section and use the already existing
"drop" label in xenvif_start_xmit() for dropping the SKB. At the
same time replace the dev_kfree_skb() call there with a call of
dev_kfree_skb_any(), as xenvif_start_xmit() can be called with
disabled interrupts.

This is XSA-424 / CVE-2022-42328 / CVE-2022-42329.

BUG=b/262368890,b/262369401
TEST=presubmit,validation
RELEASE_NOTE=Fixed CVE-2022-42328,CVE-2022-42329 in the Linux kernel.

cos-patch: security-moderate
Fixes: be81992f9086 ("xen/netback: don't queue unlimited number of packages")
Reported-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Change-Id: I42ee54d4445655afa3d43589f37874960514bba7
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/40288
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Oleksandr Tymoshenko <ovt@google.com>
3 files changed