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[79.184.247.34]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6887e224afdsm319974a12.9.2026.05.21.08.46.57 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 21 May 2026 08:46:58 -0700 (PDT) From: =?UTF-8?q?Dominik=20Wo=C5=BAniak?= To: chuck.lever@oracle.com Cc: jlayton@kernel.org, neil@brown.name, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] nfsd: check get_user() return when reading princhashlen Date: Thu, 21 May 2026 17:46:56 +0200 Message-ID: <20260521154656.63861-1-stalion@gmail.com> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In __cld_pipe_inprogress_downcall(), the get_user() that reads princhashlen from the userspace cld_msg_v2 buffer does not check its return value. A failing copy leaves princhashlen with uninitialised stack contents, which are then used to drive memdup_user() and stored as princhash.len on the resulting reclaim record. The other get_user() calls in this function all check the return; only this one is missed, which is most likely a copy-paste oversight from when v2 upcalls were introduced. Mirror the existing pattern used a few lines above for namelen. namecopy is declared with __free(kfree) so the early return cleans up the already-allocated buffer automatically. Fixes: 6ee95d1c8991 ("nfsd: add support for upcall version 2") Signed-off-by: Dominik Woźniak --- fs/nfsd/nfs4recover.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c index b338473d6e52..6ea25a52d2f4 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -718,7 +718,8 @@ __cld_pipe_inprogress_downcall(const struct cld_msg_v2 __user *cmsg, return PTR_ERR(namecopy); name.data = namecopy; name.len = namelen; - get_user(princhashlen, &ci->cc_princhash.cp_len); + if (get_user(princhashlen, &ci->cc_princhash.cp_len)) + return -EFAULT; if (princhashlen > 0) { princhashcopy = memdup_user( &ci->cc_princhash.cp_data, -- 2.50.1 (Apple Git-155)