From nobody Sun Feb 8 16:31:57 2026 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 297D5762D7 for ; Thu, 18 Apr 2024 23:20:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713482442; cv=none; b=qEgv5jYAEvXPYBYnImgzQj9uEz+4jJpK9r2vD3CWQvRx5196ARnSaWmvHeu6KtBewNW63BB1GIOUY2NbX4WPJWEG0nk4VR1g+bOimPOcywHN5C1tQRENx9G7N78gZmTU8iZozGYr/WL5puXNazaWyx4XqGGR837vIGo7iAJ9Lhk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713482442; c=relaxed/simple; bh=Q+72qrXtm3Xqm1QYlQ/ARcpBQmoPZPgK3ApUYdbDx7c=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=R9jxBbxjMU6eq3UnFYLx7pQCCdjOJfiSj1U9Xu3VPWVML4TKvUZ4hZd2OiBo4F7q4M7zgnJWNLd2Hl35/s9KWmn4zLszO/ZgxOWQumJH1uL7R+HAXW/faw62K8BA5VA4Esdr1FelLHijwFgjzB7o94+yhWTDAmXbZCntzIYNH9c= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edliaw.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=2WSGbe+l; arc=none smtp.client-ip=209.85.128.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edliaw.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="2WSGbe+l" Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-61aecbcb990so27440577b3.1 for ; Thu, 18 Apr 2024 16:20:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1713482440; x=1714087240; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=K9HSeHzPuGtWyHVXG0SBH6UyvQOr79hE7Vg79sXvjgU=; b=2WSGbe+lgquQp/VFNauRnLmTTFiykoWFbsEvN+waloQqhnLNwhTtv3BW8m7p01mHc6 qrZMi8sTe0gHcP5yJLjJmUK+l3teVVlKkaxqIk3FaN/Q2CyImGqm8HKNsVlPnFUr0/GO p1SYqqOkZ/DH+zELOqjK9988QGyDtb109H7gZZrOErLmqZEmvolgix0+dwNCXZlK7+1e OhIVoZFMd40HoPYXmC53bm8UTLsu2GB4AdkcBw+tU9KIJ+odi49mvS0hzrhJYa2twhvP u/arTdaX/rsMpnTbubG/pi2SdL5Zx/RSOY98YIFt48nrZ1UajoTEMua7wonnhf938YZd 48sw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1713482440; x=1714087240; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=K9HSeHzPuGtWyHVXG0SBH6UyvQOr79hE7Vg79sXvjgU=; b=slzQY+YpexKDlIniys36UYJp3WVMyjoqVFtUE3yNQo+VTe8RmEh8dZNLKGcPLUjRZb jDPYsPZW2SnBjhia/o4Z+VdmbAk3/BJV+XM9Ix4oCAdsHAz6DM4png3pQrpSqIzjW9/W 165vGg71LL5Eo+20h69qzEYfqYn/AJlZyNOdWlbif+MxTdEGwlpNDyHRNuNnG9PUoMqv wVnuQp9Ed2WFR71xRj/HW3Zf1qLPgCLti5oEOZwPYm7UaaGxumB/El+If86B033ZHmu5 KQJEJJbtjLXXluTo9XyvwuwLbAjWTPx46O7E4hu6Wcq436pYJ5qr1RYyZqe5OFK5p9/j +rMw== X-Forwarded-Encrypted: i=1; AJvYcCWeDn3R0q0PRI8B84fSu7unowrm2NbSLD+6ewpUOaLehfPZk0dBJeCaUXYOmVZuITE4GsBmMAO9PHn84u67AB+1PoJUIqa0hyVc6SnI X-Gm-Message-State: AOJu0Yw/+LAtlwcg4GP8dbDEhgkGbwuiJcOMo6UQf3IdkmmI9DC3hN07 SFOsi4qMk5NK7de98S3Yswq+8tSLDEc9KI58Ok9waivZnLPyL+u58iQRPEf5CwekMOSGjm5HKZC kCw== X-Google-Smtp-Source: AGHT+IFVENWOQrhyE9ZFDpAXDlThECm3CQcbnYXp2g9WsRBiAe+oNdRYITno5N/z+Nt1e8YR6fxhOoF7uMs= X-Received: from edliaw.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:305d]) (user=edliaw job=sendgmr) by 2002:a81:52c6:0:b0:61b:3a8:330f with SMTP id g189-20020a8152c6000000b0061b03a8330fmr112441ywb.5.1713482440230; Thu, 18 Apr 2024 16:20:40 -0700 (PDT) Date: Thu, 18 Apr 2024 23:19:50 +0000 In-Reply-To: <20240418232005.34244-1-edliaw@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <16430256912363@kroah.com> <20240418232005.34244-1-edliaw@google.com> X-Mailer: git-send-email 2.44.0.769.g3c40516874-goog Message-ID: <20240418232005.34244-5-edliaw@google.com> Subject: [PATCH 5.15.y v3 4/5] bpf: Fix out of bounds access for ringbuf helpers From: Edward Liaw To: stable@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa Cc: bpf@vger.kernel.org, kernel-team@android.com, Edward Liaw , Yonghong Song , linux-kernel@vger.kernel.org, tr3e.wang@gmail.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Daniel Borkmann Both bpf_ringbuf_submit() and bpf_ringbuf_discard() have ARG_PTR_TO_ALLOC_M= EM in their bpf_func_proto definition as their first argument. They both expect the result from a prior bpf_ringbuf_reserve() call which has a return type = of RET_PTR_TO_ALLOC_MEM_OR_NULL. Meaning, after a NULL check in the code, the verifier will promote the regi= ster type in the non-NULL branch to a PTR_TO_MEM and in the NULL branch to a kno= wn zero scalar. Generally, pointer arithmetic on PTR_TO_MEM is allowed, so the latter could have an offset. The ARG_PTR_TO_ALLOC_MEM expects a PTR_TO_MEM register type. However, the n= on- zero result from bpf_ringbuf_reserve() must be fed into either bpf_ringbuf_= submit() or bpf_ringbuf_discard() but with the original offset given it will then re= ad out the struct bpf_ringbuf_hdr mapping. The verifier missed to enforce a zero offset, so that out of bounds access can be triggered which could be used to escalate privileges if unprivileged BPF was enabled (disabled by default in kernel). Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support f= or it") Reported-by: (SecCoder Security Lab) Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Acked-by: Alexei Starovoitov (cherry picked from commit 64620e0a1e712a778095bd35cbb277dc2259281f) Signed-off-by: Edward Liaw --- kernel/bpf/verifier.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8cd265d1df34..33fb379b9f58 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5340,9 +5340,15 @@ static int check_func_arg(struct bpf_verifier_env *e= nv, u32 arg, case PTR_TO_BUF: case PTR_TO_BUF | MEM_RDONLY: case PTR_TO_STACK: + /* Some of the argument types nevertheless require a + * zero register offset. + */ + if (arg_type =3D=3D ARG_PTR_TO_ALLOC_MEM) + goto force_off_check; break; /* All the rest must be rejected: */ default: +force_off_check: err =3D __check_ptr_off_reg(env, reg, regno, type =3D=3D PTR_TO_BTF_ID); if (err < 0) --=20 2.44.0.769.g3c40516874-goog