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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id lt11-20020a17090b354b00b0020ad86f4c54sm1805746pjb.16.2022.11.23.11.12.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Nov 2022 11:12:07 -0800 (PST) Date: Wed, 23 Nov 2022 19:12:03 +0000 From: Carlos Llamas To: "Jiazi.Li" Cc: Greg Kroah-Hartman , arve@android.com, Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , "Jiazi.Li" , linux-kernel@vger.kernel.org Subject: Re: [PATCH] binder: remove unneeded size check code Message-ID: References: <20221115120351.2769-1-jiazi.li@transsion.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221115120351.2769-1-jiazi.li@transsion.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 15, 2022 at 08:03:51PM +0800, Jiazi.Li wrote: > In binder_ioctl function, the legitimacy check of cmd size has been > done in switch-case code: > switch (cmd) { > case BINDER_WRITE_READ;//BINDER_WRITE_READ contains size info > > So unneeded do size check in binder_ioctl and binder_ioctl_write_read > again. > > In the following version of Google GKI: > > Linux version 5.10.110-android12-9-00011-g2c814f559132-ab8969555 > > It seems that the compiler has made optimization and has not passed > cmd parameters to binder_ioctl_write_read: > : mov w8, #0x6201 // #25089 > : movk w8, #0xc030, lsl #16 > : cmp w20, w8 > : b.ne 0xffffffda8aa97880 > : mov x0, x23 //filp > : mov x1, x27 //arg > : mov x2, x22 //thread > : bl 0xffffffda8aa9e6e4 > : mov w26, w0 > > Signed-off-by: Jiazi.Li > --- > drivers/android/binder.c | 15 ++------------- > 1 file changed, 2 insertions(+), 13 deletions(-) > > diff --git a/drivers/android/binder.c b/drivers/android/binder.c > index 880224ec6abb..48e5a3531282 100644 > --- a/drivers/android/binder.c > +++ b/drivers/android/binder.c > @@ -5006,20 +5006,14 @@ static __poll_t binder_poll(struct file *filp, > return 0; > } > > -static int binder_ioctl_write_read(struct file *filp, > - unsigned int cmd, unsigned long arg, > +static int binder_ioctl_write_read(struct file *filp, unsigned long arg, > struct binder_thread *thread) > { > int ret = 0; > struct binder_proc *proc = filp->private_data; > - unsigned int size = _IOC_SIZE(cmd); > void __user *ubuf = (void __user *)arg; > struct binder_write_read bwr; > > - if (size != sizeof(struct binder_write_read)) { > - ret = -EINVAL; > - goto out; > - } > if (copy_from_user(&bwr, ubuf, sizeof(bwr))) { > ret = -EFAULT; > goto out; > @@ -5296,7 +5290,6 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > int ret; > struct binder_proc *proc = filp->private_data; > struct binder_thread *thread; > - unsigned int size = _IOC_SIZE(cmd); > void __user *ubuf = (void __user *)arg; > > /*pr_info("binder_ioctl: %d:%d %x %lx\n", > @@ -5318,7 +5311,7 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > > switch (cmd) { > case BINDER_WRITE_READ: > - ret = binder_ioctl_write_read(filp, cmd, arg, thread); > + ret = binder_ioctl_write_read(filp, arg, thread); > if (ret) > goto err; > break; > @@ -5361,10 +5354,6 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > case BINDER_VERSION: { > struct binder_version __user *ver = ubuf; > > - if (size != sizeof(struct binder_version)) { > - ret = -EINVAL; > - goto err; > - } > if (put_user(BINDER_CURRENT_PROTOCOL_VERSION, > &ver->protocol_version)) { > ret = -EINVAL; > -- > 2.17.1 > Looks good, thanks! Acked-by: Carlos Llamas