| Message ID | 20210729143532.47240-1-gregkh@linuxfoundation.org |
|---|---|
| State | Accepted |
| Commit | 86ff25ed6cd8240d18df58930bd8848b19fce308 |
| Headers | show |
| Series | [v2] i2c: dev: zero out array used for i2c reads from userspace | expand |
On Thu, Jul 29, 2021 at 04:35:32PM +0200, Greg Kroah-Hartman wrote: > 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 <edumazet@google.com> > Cc: Dan Carpenter <dan.carpenter@oracle.com> > Cc: stable <stable@vger.kernel.org> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Fixed checkpatch warning "WARNING: Invalid email format for stable: 'stable <stable@vger.kernel.org>', prefer 'stable@vger.kernel.org' " and applied to for-current, thanks!
On Tue, Aug 10, 2021 at 10:55:11PM +0200, Wolfram Sang wrote: > On Thu, Jul 29, 2021 at 04:35:32PM +0200, Greg Kroah-Hartman wrote: > > 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 <edumazet@google.com> > > Cc: Dan Carpenter <dan.carpenter@oracle.com> > > Cc: stable <stable@vger.kernel.org> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Fixed checkpatch warning "WARNING: Invalid email format for stable: > 'stable <stable@vger.kernel.org>', prefer 'stable@vger.kernel.org' " and > applied to for-current, thanks! That is a crazy warning, never even knew it was there. But as the stable maintainer, it does not look correct as both are just fine... Anyway, thanks for taking the patch! greg k-h
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c index cb64fe649390..77f576e51652 100644 --- a/drivers/i2c/i2c-dev.c +++ b/drivers/i2c/i2c-dev.c @@ -141,7 +141,7 @@ 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; @@ -150,7 +150,8 @@ 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; }
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 <edumazet@google.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- v2: Add copy_to_user() change as pointed out by Dan drivers/i2c/i2c-dev.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)