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[81.38.138.95]) by smtp.gmail.com with ESMTPSA id r12-20020a5d6c6c000000b00203ec2b1255sm16241799wrz.60.2022.03.28.10.00.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Mar 2022 10:00:02 -0700 (PDT) From: "Jorge Ramirez-Ortiz, Gmail" X-Google-Original-From: "Jorge Ramirez-Ortiz, Gmail" Date: Mon, 28 Mar 2022 19:00:01 +0200 To: Xiaomeng Tong Cc: srinivas.kandagatla@linaro.org, amahesh@qti.qualcomm.com, arnd@arndb.de, gregkh@linuxfoundation.org, jorge.ramirez-ortiz@linaro.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] misc: fastrpc: fix an incorrect NULL check on list iterator Message-ID: <20220328170001.GA3040725@trex> References: <20220327062202.5720-1-xiam0nd.tong@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220327062202.5720-1-xiam0nd.tong@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 27/03/22, Xiaomeng Tong wrote: > The bug is here: > if (!buf) { > > The list iterator value 'buf' will *always* be set and non-NULL > by list_for_each_entry(), so it is incorrect to assume that the > iterator value will be NULL if the list is empty (in this case, the > check 'if (!buf) {' will always be false and never exit expectly). yes. > > To fix the bug, use a new variable 'iter' as the list iterator, > while use the original variable 'buf' as a dedicated pointer to > point to the found element. LGTM > > Cc: stable@vger.kernel.org > Fixes: 2419e55e532de ("misc: fastrpc: add mmap/unmap support") > Signed-off-by: Xiaomeng Tong > --- > drivers/misc/fastrpc.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > index aa1682b94a23..45aaf54a7560 100644 > --- a/drivers/misc/fastrpc.c > +++ b/drivers/misc/fastrpc.c > @@ -1353,17 +1353,18 @@ static int fastrpc_req_munmap_impl(struct fastrpc_user *fl, > struct fastrpc_req_munmap *req) > { > struct fastrpc_invoke_args args[1] = { [0] = { 0 } }; > - struct fastrpc_buf *buf, *b; > + struct fastrpc_buf *buf = NULL, *iter, *b; > struct fastrpc_munmap_req_msg req_msg; > struct device *dev = fl->sctx->dev; > int err; > u32 sc; > > spin_lock(&fl->lock); > - list_for_each_entry_safe(buf, b, &fl->mmaps, node) { > - if ((buf->raddr == req->vaddrout) && (buf->size == req->size)) > + list_for_each_entry_safe(iter, b, &fl->mmaps, node) { > + if ((iter->raddr == req->vaddrout) && (iter->size == req->size)) { > + buf = iter; > break; > - buf = NULL; > + } > } > spin_unlock(&fl->lock); > > -- > 2.17.1 >