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[107.190.31.17]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c9e91b0a2c4sm6115711a12.19.2026.07.06.09.57.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 06 Jul 2026 09:57:13 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 06 Jul 2026 12:57:12 -0400 Message-Id: Cc: "Martin KaFai Lau" , "Song Liu" , "Yonghong Song" , "Jiri Olsa" , "Emil Tsalapatis" , "Puranjay Mohan" , , , Subject: Re: [PATCH bpf-next 1/2] bpf: Reject out-of-range arena free addresses From: "Emil Tsalapatis" To: "Nuoqi Gui" , "Alexei Starovoitov" , "Daniel Borkmann" , "Andrii Nakryiko" , "Eduard Zingerman" , "Kumar Kartikeya Dwivedi" , "Shuah Khan" X-Mailer: aerc 0.21.0-0-g5549850facc2 References: <20260706-f01-31-arena-free-bpf-next-v1-0-3ad6e7384285@mails.tsinghua.edu.cn> <20260706-f01-31-arena-free-bpf-next-v1-1-3ad6e7384285@mails.tsinghua.edu.cn> In-Reply-To: <20260706-f01-31-arena-free-bpf-next-v1-1-3ad6e7384285@mails.tsinghua.edu.cn> On Mon Jul 6, 2026 at 11:52 AM EDT, Nuoqi Gui wrote: > bpf_arena_free_pages() accepts scalar arena addresses. The free path > masks the low 32 bits, computes the full user address, and clips only > against arena->user_vm_end before inserting the range into the arena > free range tree. > > A scalar address below arena->user_vm_start can therefore produce an > out-of-domain page offset. A later allocation can consume that offset > from the free range tree and return an address outside the arena range. > > Reject frees whose computed full address is below the arena start before > clipping the end of the range. > > Fixes: 317460317a02 ("bpf: Introduce bpf_arena.") > Signed-off-by: Nuoqi Gui This is the exact same patch that Yiyang Chen sent about a week ago. pw-bot: cr > --- > kernel/bpf/arena.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c > index 80b7b8a69446..97a5d8d21295 100644 > --- a/kernel/bpf/arena.c > +++ b/kernel/bpf/arena.c > @@ -853,6 +853,8 @@ static void arena_free_pages(struct bpf_arena *arena,= long uaddr, long page_cnt, > uaddr &=3D PAGE_MASK; > kaddr =3D bpf_arena_get_kern_vm_start(arena) + uaddr; > full_uaddr =3D clear_lo32(arena->user_vm_start) + uaddr; > + if (full_uaddr < arena->user_vm_start) > + return; > uaddr_end =3D min(arena->user_vm_end, full_uaddr + (page_cnt << PAGE_SH= IFT)); > if (full_uaddr >=3D uaddr_end) > return;