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 D899A18DB2A; Wed, 25 Feb 2026 01:33:34 +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=1771983214; cv=none; b=KMad4Mp+p5P2Drma8bfRPhoHg0Bx3kiF3k1DLLoKYFDskCSn+JK5ZlAPd5yKKJlKOJ7aBnNO8PXaz9TSKF6zyeKgL6M9HC+eh+NMG+eY6R6o00sCbWWVqcS15vSWRp6ckTRnLuTVB1TZNo2AWhBPXDiKWUsNEa3ah4FHFj/5uUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771983214; c=relaxed/simple; bh=RU//DBNy43mBR2b6xVbEUWoKkwbqlRwztNYlLiHnSZ0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=URPXjUKyMrf/RhNTT0FOFeEO8pMJ/9fmwKn4eRGpUuNexa4Tj6xofXFWZJsOqGR0lX5P3zuIz+04KwyrHM5JW8pZQFHOdLI/YE6wzGCk/OGL5ZTLv0owU14U16lwZUEL/UQ/rO0mGRWqzwIaorn8TX2ZGch4uW9Vr4wqsvCVy4Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WFnkqCnL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WFnkqCnL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9165AC116D0; Wed, 25 Feb 2026 01:33:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1771983214; bh=RU//DBNy43mBR2b6xVbEUWoKkwbqlRwztNYlLiHnSZ0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WFnkqCnL6z8iaXdtVcvrjw9qapKBKh9n/aF4fq3ZRQxl6pp756bFjBI3+ZqwY38/z V23PXpqYgJ0jKwNVzZGOFOiEjQUfK1R9tw8v9BKnsf4Dbl3I+C/WasnCXfWl5CBvqs VBQA+5XkhuIHnupO/I5eZZoTKtmRSEAGhunl4yQw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Anthony Iliopoulos , NeilBrown , Chuck Lever , Sasha Levin Subject: [PATCH 6.19 363/781] nfsd: never defer requests during idmap lookup Date: Tue, 24 Feb 2026 17:17:52 -0800 Message-ID: <20260225012408.586215217@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260225012359.695468795@linuxfoundation.org> References: <20260225012359.695468795@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Anthony Iliopoulos [ Upstream commit f9c206cdc4266caad6a9a7f46341420a10f03ccb ] During v4 request compound arg decoding, some ops (e.g. SETATTR) can trigger idmap lookup upcalls. When those upcall responses get delayed beyond the allowed time limit, cache_check() will mark the request for deferral and cause it to be dropped. This prevents nfs4svc_encode_compoundres from being executed, and thus the session slot flag NFSD4_SLOT_INUSE never gets cleared. Subsequent client requests will fail with NFSERR_JUKEBOX, given that the slot will be marked as in-use, making the SEQUENCE op fail. Fix this by making sure that the RQ_USEDEFERRAL flag is always clear during nfs4svc_decode_compoundargs(), since no v4 request should ever be deferred. Fixes: 2f425878b6a7 ("nfsd: don't use the deferral service, return NFS4ERR_DELAY") Signed-off-by: Anthony Iliopoulos Reviewed-by: NeilBrown Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/nfs4idmap.c | 48 +++++++++++++++++++++++++++++++++++++++------ fs/nfsd/nfs4proc.c | 2 -- fs/nfsd/nfs4xdr.c | 16 +++++++++++++++ 3 files changed, 58 insertions(+), 8 deletions(-) diff --git a/fs/nfsd/nfs4idmap.c b/fs/nfsd/nfs4idmap.c index 8cca1329f3485..b5b3d45979c9b 100644 --- a/fs/nfsd/nfs4idmap.c +++ b/fs/nfsd/nfs4idmap.c @@ -643,13 +643,31 @@ static __be32 encode_name_from_id(struct xdr_stream *xdr, return idmap_id_to_name(xdr, rqstp, type, id); } -__be32 -nfsd_map_name_to_uid(struct svc_rqst *rqstp, const char *name, size_t namelen, - kuid_t *uid) +/** + * nfsd_map_name_to_uid - Map user@domain to local UID + * @rqstp: RPC execution context + * @name: user@domain name to be mapped + * @namelen: length of name, in bytes + * @uid: OUT: mapped local UID value + * + * Returns nfs_ok on success or an NFSv4 status code on failure. + */ +__be32 nfsd_map_name_to_uid(struct svc_rqst *rqstp, const char *name, + size_t namelen, kuid_t *uid) { __be32 status; u32 id = -1; + /* + * The idmap lookup below triggers an upcall that invokes + * cache_check(). RQ_USEDEFERRAL must be clear to prevent + * cache_check() from setting RQ_DROPME via svc_defer(). + * NFSv4 servers are not permitted to drop requests. Also + * RQ_DROPME will force NFSv4.1 session slot processing to + * be skipped. + */ + WARN_ON_ONCE(test_bit(RQ_USEDEFERRAL, &rqstp->rq_flags)); + if (name == NULL || namelen == 0) return nfserr_inval; @@ -660,13 +678,31 @@ nfsd_map_name_to_uid(struct svc_rqst *rqstp, const char *name, size_t namelen, return status; } -__be32 -nfsd_map_name_to_gid(struct svc_rqst *rqstp, const char *name, size_t namelen, - kgid_t *gid) +/** + * nfsd_map_name_to_gid - Map user@domain to local GID + * @rqstp: RPC execution context + * @name: user@domain name to be mapped + * @namelen: length of name, in bytes + * @gid: OUT: mapped local GID value + * + * Returns nfs_ok on success or an NFSv4 status code on failure. + */ +__be32 nfsd_map_name_to_gid(struct svc_rqst *rqstp, const char *name, + size_t namelen, kgid_t *gid) { __be32 status; u32 id = -1; + /* + * The idmap lookup below triggers an upcall that invokes + * cache_check(). RQ_USEDEFERRAL must be clear to prevent + * cache_check() from setting RQ_DROPME via svc_defer(). + * NFSv4 servers are not permitted to drop requests. Also + * RQ_DROPME will force NFSv4.1 session slot processing to + * be skipped. + */ + WARN_ON_ONCE(test_bit(RQ_USEDEFERRAL, &rqstp->rq_flags)); + if (name == NULL || namelen == 0) return nfserr_inval; diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index 9ec08dd4fe823..f780024f9a088 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -3011,8 +3011,6 @@ nfsd4_proc_compound(struct svc_rqst *rqstp) BUG_ON(cstate->replay_owner); out: cstate->status = status; - /* Reset deferral mechanism for RPC deferrals */ - set_bit(RQ_USEDEFERRAL, &rqstp->rq_flags); return rpc_success; } diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 51ef97c254568..5065727204b95 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -6013,6 +6013,22 @@ nfs4svc_decode_compoundargs(struct svc_rqst *rqstp, struct xdr_stream *xdr) args->ops = args->iops; args->rqstp = rqstp; + /* + * NFSv4 operation decoders can invoke svc cache lookups + * that trigger svc_defer() when RQ_USEDEFERRAL is set, + * setting RQ_DROPME. This creates two problems: + * + * 1. Non-idempotency: Compounds make it too hard to avoid + * problems if a request is deferred and replayed. + * + * 2. Session slot leakage (NFSv4.1+): If RQ_DROPME is set + * during decode but SEQUENCE executes successfully, the + * session slot will be marked INUSE. The request is then + * dropped before encoding, so the slot is never released, + * rendering it permanently unusable by the client. + */ + clear_bit(RQ_USEDEFERRAL, &rqstp->rq_flags); + return nfsd4_decode_compound(args); } -- 2.51.0