From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f177.google.com (mail-pl1-f177.google.com [209.85.214.177]) (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 3A33B199250 for ; Thu, 20 Jun 2024 10:28:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718879318; cv=none; b=T3IeY+GXYCEpgNjEORkM/WoOgslCvW2RCGCm5UqtXsL7Qfj8jLnzRiMeMiQQSKNY3IY8xmsOYLhsc+hu4kTx26vYrWr1LPq2KVQPWAkE2N/o0ymcRiOQEbnXJPdp1gZ4HHgtnUbYdyN8CfTFQ65J9H3rptpijfiRZQrvAGOHYKg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718879318; c=relaxed/simple; bh=8orZamx8oVHw4rR7aN8XdwgGxp218vaZRASmnxXrnlU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=pxwHFAyYQng2ZEO+Ss0O7JkdgrYGQA5nMfWXSc1SiMf8GbZmoMvfnKiM0qyS3j2tmxF9nkHN7Ax3PN7eWDtptgPuS0fjRg+QOURu1uoDYOmd9T4MCoTEevKQ3cX35jDvyk4jga5O2qO6KU25gfssyexe/FQe8eid2MFTOm8gU8A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=KJrkUpcp; arc=none smtp.client-ip=209.85.214.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KJrkUpcp" Received: by mail-pl1-f177.google.com with SMTP id d9443c01a7336-1f700e4cb92so6463905ad.2 for ; Thu, 20 Jun 2024 03:28:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1718879316; x=1719484116; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=7OjfKW4mhlHyaNhimmDxBtVqtRhMmyAv6HPN10uZ00c=; b=KJrkUpcp/PS9iVNrTMqqOvZWAP3MnqH/BDvx3bctx2wygJtkdMGgfnMbDpv8dmeUVv e1Q+pc8I3UBNMhQylcEchoxEC6RGg8xDy604TQM+RmPsfVJXTr297JH7ZrbA2mPso3BW Ix7UsWqSR5M0B9fglA/3B6E2aUjILi0qyPUN9Suc+um+FRTDc4AQwKjeKHkumCIYszCx PRjPpGYhnNXl+GTCGi2MnbsGEwhqvgaUc4RoFvmaZ1RZdMXjHQPZKMgx372qB7uZssUV Fcfpl9K7P5PeLSMnpWfvO1tt8sxAyNVNRotxLwzWo9WOQ6NjYNy+lwUyzHfWxP2sfSRx BEtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1718879316; x=1719484116; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=7OjfKW4mhlHyaNhimmDxBtVqtRhMmyAv6HPN10uZ00c=; b=ProFbP2vVCFfEX9byPMMoUdGN9XBLp+5LKjP3QpdB2befdSqQVqfck4veG4D5Ql4M9 2eNk7Dc5R7abjHXiC4BbqkN2PcGuYxSlbx1XZQVDbFlbM5Op9TTTUniRBFpGiEHmwKf3 TEw0Yg9lBdUFgiBk59+Onfxis/yldOojLF1YJjYyjO7YxcohfFjkzSK7juiSZszC4Sre ywGgs85ae4WA9PZAx2Y3kBwbek7J6l2D3Mk8NRd+Znq/Cw9CiFozaLV3KcjmaCwqFXxN LQ4H5MKuGC1VXsAaDz4SI3O5B5wu5XoK49Ip0LvjTPZdZEqOHE2c/F3gImOEZ+irC7dp eb8Q== X-Forwarded-Encrypted: i=1; AJvYcCXu2DyFmQVMmxv1+mx5ILeUC6NYbyE2pp2XL5606EcRfscqu4mKZOlFnuBWsAauOXPIqf0Ky5Rn29bxWLmSVm/cIoCq X-Gm-Message-State: AOJu0YzBUuWac44aAA09rDLHAUCcjLS/Qey7K6iCQSpOEI4fLgTcR9SE c28Lau15S07HmIV+XIB2C/UEpYbzrSDqBbZ2MjJ46+WUViUANZkv X-Google-Smtp-Source: AGHT+IH0k907BnGQJH7TB6x/UlD/v0AtFrGWcHf8hXZ41SyievNCtHsMQWXKzwpK4dvQwq2YE20L7g== X-Received: by 2002:a17:902:e80a:b0:1f9:c9e2:4e1 with SMTP id d9443c01a7336-1f9c9e20740mr13483835ad.66.1718879316326; Thu, 20 Jun 2024 03:28:36 -0700 (PDT) Received: from [10.22.68.7] ([122.11.166.8]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1f99261d056sm50805305ad.86.2024.06.20.03.28.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Jun 2024 03:28:35 -0700 (PDT) Message-ID: Date: Thu, 20 Jun 2024 18:28:30 +0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf] bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT To: Tengda Wu , bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa References: <20240620060701.1465291-1-wutengda@huaweicloud.com> Content-Language: en-US From: Leon Hwang In-Reply-To: <20240620060701.1465291-1-wutengda@huaweicloud.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 20/6/24 14:07, Tengda Wu wrote: > When loading a EXT program without specifying `attr->attach_prog_fd`, > the `prog->aux->dst_prog` will be null. At this time, calling > resolve_prog_type() anywhere will result in a null pointer dereference. > > Example stack trace: > > [ 8.107863] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004 > [ 8.108262] Mem abort info: > [ 8.108384] ESR = 0x0000000096000004 > [ 8.108547] EC = 0x25: DABT (current EL), IL = 32 bits > [ 8.108722] SET = 0, FnV = 0 > [ 8.108827] EA = 0, S1PTW = 0 > [ 8.108939] FSC = 0x04: level 0 translation fault > [ 8.109102] Data abort info: > [ 8.109203] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 > [ 8.109399] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 > [ 8.109614] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 > [ 8.109836] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000101354000 > [ 8.110011] [0000000000000004] pgd=0000000000000000, p4d=0000000000000000 > [ 8.112624] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP > [ 8.112783] Modules linked in: > [ 8.113120] CPU: 0 PID: 99 Comm: may_access_dire Not tainted 6.10.0-rc3-next-20240613-dirty #1 > [ 8.113230] Hardware name: linux,dummy-virt (DT) > [ 8.113390] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 8.113429] pc : may_access_direct_pkt_data+0x24/0xa0 > [ 8.113746] lr : add_subprog_and_kfunc+0x634/0x8e8 > [ 8.113798] sp : ffff80008283b9f0 > [ 8.113813] x29: ffff80008283b9f0 x28: ffff800082795048 x27: 0000000000000001 > [ 8.113881] x26: ffff0000c0bb2600 x25: 0000000000000000 x24: 0000000000000000 > [ 8.113897] x23: ffff0000c1134000 x22: 000000000001864f x21: ffff0000c1138000 > [ 8.113912] x20: 0000000000000001 x19: ffff0000c12b8000 x18: ffffffffffffffff > [ 8.113929] x17: 0000000000000000 x16: 0000000000000000 x15: 0720072007200720 > [ 8.113944] x14: 0720072007200720 x13: 0720072007200720 x12: 0720072007200720 > [ 8.113958] x11: 0720072007200720 x10: 0000000000f9fca4 x9 : ffff80008021f4e4 > [ 8.113991] x8 : 0101010101010101 x7 : 746f72705f6d656d x6 : 000000001e0e0f5f > [ 8.114006] x5 : 000000000001864f x4 : ffff0000c12b8000 x3 : 000000000000001c > [ 8.114020] x2 : 0000000000000002 x1 : 0000000000000000 x0 : 0000000000000000 > [ 8.114126] Call trace: > [ 8.114159] may_access_direct_pkt_data+0x24/0xa0 > [ 8.114202] bpf_check+0x3bc/0x28c0 > [ 8.114214] bpf_prog_load+0x658/0xa58 > [ 8.114227] __sys_bpf+0xc50/0x2250 > [ 8.114240] __arm64_sys_bpf+0x28/0x40 > [ 8.114254] invoke_syscall.constprop.0+0x54/0xf0 > [ 8.114273] do_el0_svc+0x4c/0xd8 > [ 8.114289] el0_svc+0x3c/0x140 > [ 8.114305] el0t_64_sync_handler+0x134/0x150 > [ 8.114331] el0t_64_sync+0x168/0x170 > [ 8.114477] Code: 7100707f 54000081 f9401c00 f9403800 (b9400403) > [ 8.118672] ---[ end trace 0000000000000000 ]--- > > Fix this by adding dst_prog non-empty check in BPF_PROG_TYPE_EXT case > when calling bpf_prog_load(). > > Fixes: 4a9c7bbe2ed4 ("bpf: Resolve to prog->aux->dst_prog->type only for BPF_PROG_TYPE_EXT") > Signed-off-by: Tengda Wu > Cc: stable@vger.kernel.org # v5.18+ > --- > kernel/bpf/syscall.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index f45ed6adc092..4490f8ccf006 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -2632,9 +2632,12 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type, > return 0; > return -EINVAL; > case BPF_PROG_TYPE_SYSCALL: > - case BPF_PROG_TYPE_EXT: > if (expected_attach_type) > return -EINVAL; > + return 0; > + case BPF_PROG_TYPE_EXT: > + if (expected_attach_type || !dst_prog) > + return -EINVAL; > fallthrough; > default: > return 0; Would be better to add a selftest for it. But, looks good to me. Acked-by: Leon Hwang