From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E94391FAC29; Tue, 14 Jan 2025 19:27:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736882873; cv=none; b=WOQzySdYanTDDc+0lgNYrbE3FoF6L81P/Bk11WcdEewfiE5tmszBWPQ9ZOc9hVMzZNJ9pvZmlXRmwbPXVHfXXGjydus9Y6zroVRcNnWVG3ouFO3Q0ZwckBxVrFrlkzvh20roTcXDw1q2b/n0VJLKB16kI4jxrIdsFlT7vBWt0Fw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736882873; c=relaxed/simple; bh=GZdGtAQK0Lu1HKDFmrTlLUDpUdXyPKFX4fODXIAxX2A=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=DhsYPyMMj4n93hzatbZcwnX077YzA7NqQf7qNMO7Bmmk6pFe8Ul48mqgQ85bcmhbZ0JyftrnsjiJScvJqquZhVna0m1vvFOxzq6vnxHTSm6Lj3uXgJG2LcOmhygLbfGfVTNR38P8KgUkE679DDM/XSIjT18NrENPH7Jb3+vNy6g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AIhOrpjn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="AIhOrpjn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E721C4CEDD; Tue, 14 Jan 2025 19:27:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736882872; bh=GZdGtAQK0Lu1HKDFmrTlLUDpUdXyPKFX4fODXIAxX2A=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=AIhOrpjnO28NMdWiSThvIv7MUOn3ZrG6TROxgac5pIJ/GWwEbO7J7mlutxTEm/Zy5 K5cQ6ciSsJMRf6IlNU9EqllsBUk2AlmxyoKwMuGH1fgCXpQzpS6tU0Hm46fhvDDLHd jl7bd2pVwkBDmeVsQZXLT5cEChpS5LT5ddOG8I7BzzRNKsOJKhGQEhtmiOijFR0g7u s8uCb10kZ/3HYW2s/GrGDfJPSapvhbSh+BsmblkIRSqBZ2Y+vABiZX4zpFN3RWTSxb gtgeBEQFXEYJDG3AApq7AR5QFlwB/OitogbTSL8jdVgkLhqZBYWiFMPU1jPm51WIZa 82AZbDMCSjZtQ== Message-ID: <8864761c99553a7f18adc13e98b4ef6255da1d9e.camel@kernel.org> Subject: Re: [PATCH] nfsd: free nfsd_file by gc after adding it to lru list From: Jeff Layton To: Li Lingfeng , chuck.lever@oracle.com, neilb@suse.de, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai1@huaweicloud.com, houtao1@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com, lilingfeng@huaweicloud.com Date: Tue, 14 Jan 2025 14:27:50 -0500 In-Reply-To: <20250113025957.1253214-1-lilingfeng3@huawei.com> References: <20250113025957.1253214-1-lilingfeng3@huawei.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv 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linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2025-01-13 at 10:59 +0800, Li Lingfeng wrote: > In nfsd_file_put, after inserting the nfsd_file into the nfsd_file_lru > list, gc may be triggered in another thread and immediately release this > nfsd_file, which will lead to a UAF when accessing this nfsd_file again. >=20 > All the places where unhash is done will also perform lru_remove, so ther= e > is no need to do lru_remove separately here. After inserting the nfsd_fil= e > into the nfsd_file_lru list, it can be released by relying on gc. >=20 > Fixes: 4a0e73e635e3 ("NFSD: Leave open files out of the filecache LRU") > Signed-off-by: Li Lingfeng > --- > fs/nfsd/filecache.c | 12 ++---------- > 1 file changed, 2 insertions(+), 10 deletions(-) >=20 > diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c > index a1cdba42c4fa..37b65cb1579a 100644 > --- a/fs/nfsd/filecache.c > +++ b/fs/nfsd/filecache.c > @@ -372,18 +372,10 @@ nfsd_file_put(struct nfsd_file *nf) > /* Try to add it to the LRU. If that fails, decrement. */ > if (nfsd_file_lru_add(nf)) { > /* If it's still hashed, we're done */ > - if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { > + if (list_lru_count(&nfsd_file_lru)) > nfsd_file_schedule_laundrette(); > - return; > - } > =20 > - /* > - * We're racing with unhashing, so try to remove it from > - * the LRU. If removal fails, then someone else already > - * has our reference. > - */ > - if (!nfsd_file_lru_remove(nf)) > - return; > + return; > } > } > if (refcount_dec_and_test(&nf->nf_ref)) I think this looks OK. Filecache bugs are particularly nasty though, so let's run this through a nice long testing cycle. Reviewed-by: Jeff Layton