From: Greg Kroah-Hartman Date: Thu, 29 Jul 2021 14:35:32 +0000 (+0200) Subject: i2c: dev: zero out array used for i2c reads from userspace X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=bc42bd9090ecbacb8ea325e25e02afdf37fc811e;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git i2c: dev: zero out array used for i2c reads from userspace commit 86ff25ed6cd8240d18df58930bd8848b19fce308 upstream. If an i2c driver happens to not provide the full amount of data that a user asks for, it is possible that some uninitialized data could be sent to userspace. While all in-kernel drivers look to be safe, just be sure by initializing the buffer to zero before it is passed to the i2c driver so that any future drivers will not have this issue. Also properly copy the amount of data recvieved to the userspace buffer, as pointed out by Dan Carpenter. Reported-by: Eric Dumazet Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Wolfram Sang Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c index c4066276eb7b..b7f9fb00f695 100644 --- a/drivers/i2c/i2c-dev.c +++ b/drivers/i2c/i2c-dev.c @@ -148,7 +148,7 @@ static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count, if (count > 8192) count = 8192; - tmp = kmalloc(count, GFP_KERNEL); + tmp = kzalloc(count, GFP_KERNEL); if (tmp == NULL) return -ENOMEM; @@ -157,7 +157,8 @@ static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count, ret = i2c_master_recv(client, tmp, count); if (ret >= 0) - ret = copy_to_user(buf, tmp, count) ? -EFAULT : ret; + if (copy_to_user(buf, tmp, ret)) + ret = -EFAULT; kfree(tmp); return ret; }