From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from abb.hmeau.com (abb.hmeau.com [144.6.53.87]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4986E57876; Tue, 2 Apr 2024 08:36:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=144.6.53.87 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712046978; cv=none; b=cijWfq5iPsLYjwBonJMjTXEuZFoulWKOsW+B3AKcxrah0RseyUT6MCHulCshgmQ95icnOFtbWrpQy5+UF+er1AHgZjHRP8RZ7eUkcts2+3uKEBbPfSRrlv+vzEaKYcpmIO1sCYDQU9MP0qT1iHVKCcTxjpzZ1msziejS3Ryg9Ao= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712046978; c=relaxed/simple; bh=UB/N0cVPnf/gh5VPq0ZazBwt+QqNOI4Qfzr3vqZ49ZY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qACvkhliKGBtfr2hAsn7Q22mpR/XFw2KfLh4tpWjtmcbb6Z4jR3rjvb+noImnylkMBpZUN+rQHiGDL5E8Xt+dqX2HnVCoJh5LUR/KF86GefZ9BktwdzspYGJViIALb6Xc0W8RDxcyTQw/ZcYEKJnC+6OY8bUBE5zHANgLDy9YIA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gondor.apana.org.au; spf=pass smtp.mailfrom=gondor.apana.org.au; arc=none smtp.client-ip=144.6.53.87 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gondor.apana.org.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gondor.apana.org.au Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.94.2 #2 (Debian)) id 1rrZcY-00E0Ns-HN; Tue, 02 Apr 2024 16:35:55 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Tue, 02 Apr 2024 16:36:11 +0800 Date: Tue, 2 Apr 2024 16:36:11 +0800 From: Herbert Xu To: xingwei lee Cc: davem@davemloft.net, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, samsun1006219@gmail.com, Mike Rapoport , Andrew Morton , Linus Torvalds , Eric Dumazet , Jakub Kicinski , netdev@vger.kernel.org Subject: Re: BUG: unable to handle kernel paging request in crypto_sha3_update Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Mar 20, 2024 at 10:57:53AM +0800, xingwei lee wrote: > > syscall(__NR_bind, /*fd=*/r[0], /*addr=*/0x20000000ul, /*addrlen=*/0x58ul); > res = syscall(__NR_accept, /*fd=*/r[0], /*peer=*/0ul, /*peerlen=*/0ul); > if (res != -1) > r[1] = res; > res = syscall(__NR_memfd_secret, /*flags=*/0ul); > if (res != -1) > r[2] = res; So this is the key to the issue. The whole point of memfd_secret is to make the pages inaccessible to the kernel. The issue is those pages are then gifted to the kernel through sendmsg. Somewhere along the line someone is supposed to throw up an error about this, or map the pages properly. I guess neither happened which is why we end up with a page fault. I'll cc the memfd_secret authors to see what should catch this. > syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0xb36000ul, > /*prot=*/0x2000003ul, /*flags=*/0x28011ul, /*fd=*/r[2], > /*offset=*/0ul); > syscall(__NR_ftruncate, /*fd=*/r[2], /*len=*/0xde99ul); > *(uint64_t*)0x20000180 = 0; > *(uint32_t*)0x20000188 = 0; > *(uint64_t*)0x20000190 = 0x20000140; > *(uint64_t*)0x20000140 = 0x20000080; > *(uint64_t*)0x20000148 = 0xb0; > *(uint64_t*)0x20000198 = 1; > *(uint64_t*)0x200001a0 = 0; > *(uint64_t*)0x200001a8 = 0; > *(uint32_t*)0x200001b0 = 0; > syscall(__NR_sendmsg, /*fd=*/r[1], /*msg=*/0x20000180ul, > /*f=*/0x47933e2b0522cf63ul); This is the spot where the memfd_secret pages are given to the kernel for processing through sendmsg. Thanks, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt