netdev - [PATCH bpf v2 0/2] Fix hashmap overflow checks for 32-bit arches

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Message-ID: <20240229112250.13723-1-toke@redhat.com>
Date: Thu, 29 Feb 2024 12:22:46 +0100
From: Toke Høiland-Jørgensen <toke@...hat.com>
To: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	"David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...gle.com>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Toke Høiland-Jørgensen <toke@...hat.com>
Cc: Jesper Dangaard Brouer <brouer@...hat.com>,
	netdev@...r.kernel.org,
	bpf@...r.kernel.org
Subject: [PATCH bpf v2 0/2] Fix hashmap overflow checks for 32-bit arches

Syzbot managed to trigger a crash by creating a DEVMAP_HASH map with a
large number of buckets because the overflow check relies on
well-defined behaviour that is only correct on 64-bit arches.

Fix the overflow checks to happen before values are rounded up.

v2:
- Fix off-by-one error in overflow check
- Apply the same fix to hashtab, where the devmap_hash code was copied
  from (John)

Toke Høiland-Jørgensen (2):
  bpf: Fix DEVMAP_HASH overflow check on 32-bit arches
  bpf: Fix hashtab overflow check on 32-bit arches

 kernel/bpf/devmap.c  |  8 +++-----
 kernel/bpf/hashtab.c | 10 +++++-----
 2 files changed, 8 insertions(+), 10 deletions(-)

-- 
2.43.2