On 2024-11-14 18:15, Luiz Augusto von Dentz wrote:
> Hi David,
>
> On Thu, Nov 14, 2024 at 7:42 PM David Wei <dw@xxxxxxxxxxx> wrote:
>>
>> On 2024-11-14 15:27, Michal Luczaj wrote:
>>> The bt_copy_from_sockptr() return value is being misinterpreted by most
>>> users: a non-zero result is mistakenly assumed to represent an error code,
>>> but actually indicates the number of bytes that could not be copied.
>>>
>>> Remove bt_copy_from_sockptr() and adapt callers to use
>>> copy_safe_from_sockptr().
>>>
>>> For sco_sock_setsockopt() (case BT_CODEC) use copy_struct_from_sockptr() to
>>> scrub parts of uninitialized buffer.
>>>
>>> Opportunistically, rename `len` to `optlen` in hci_sock_setsockopt_old()
>>> and hci_sock_setsockopt().
>>>
>>> Fixes: 51eda36d33e4 ("Bluetooth: SCO: Fix not validating setsockopt user input")
>>> Fixes: a97de7bff13b ("Bluetooth: RFCOMM: Fix not validating setsockopt user input")
>>> Fixes: 4f3951242ace ("Bluetooth: L2CAP: Fix not validating setsockopt user input")
>>> Fixes: 9e8742cdfc4b ("Bluetooth: ISO: Fix not validating setsockopt user input")
>>> Fixes: b2186061d604 ("Bluetooth: hci_sock: Fix not validating setsockopt user input")
>>> Signed-off-by: Michal Luczaj <mhal@xxxxxxx>
>>> ---
>>> include/net/bluetooth/bluetooth.h | 9 ---------
>>> net/bluetooth/hci_sock.c | 14 +++++++-------
>>> net/bluetooth/iso.c | 10 +++++-----
>>> net/bluetooth/l2cap_sock.c | 20 +++++++++++---------
>>> net/bluetooth/rfcomm/sock.c | 9 ++++-----
>>> net/bluetooth/sco.c | 11 ++++++-----
>>> 6 files changed, 33 insertions(+), 40 deletions(-)
>>>
>> ...
>>> diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
>>> index f48250e3f2e103c75d5937e1608e43c123aa3297..1001fb4cc21c0ecc7bcdd3ea9041770ede4f27b8 100644
>>> --- a/net/bluetooth/rfcomm/sock.c
>>> +++ b/net/bluetooth/rfcomm/sock.c
>>> @@ -629,10 +629,9 @@ static int rfcomm_sock_setsockopt_old(struct socket *sock, int optname,
>>>
>>> switch (optname) {
>>> case RFCOMM_LM:
>>> - if (bt_copy_from_sockptr(&opt, sizeof(opt), optval, optlen)) {
>>> - err = -EFAULT;
>>> + err = copy_safe_from_sockptr(&opt, sizeof(opt), optval, optlen);
>>> + if (err)
>>> break;
>>> - }
>>
>> This will return a positive integer if copy_safe_from_sockptr() fails.
>
> What are you talking about copy_safe_from_sockptr never returns a
> positive value:
>
> * Returns:
> * * -EINVAL: @optlen < @ksize
> * * -EFAULT: access to userspace failed.
> * * 0 : @ksize bytes were copied
Isn't this what this series is about? copy_from_sockptr() returns 0 on
success, or a positive integer for number of bytes NOT copied on error.
Patch 4 even updates the docs for copy_from_sockptr().
copy_safe_from_sockptr()
-> copy_from_sockptr()
-> copy_from_sockptr_offset()
-> memcpy() for kernel to kernel OR
-> copy_from_user() otherwise
And copy_from_user() follows the same 0 for success or N > 0 for
failure. It does not EFAULT on its own AFAIK.
The docs for copy_safe_from_sockptr() that you've linked contains the
exact misunderstanding that Michal is correcting.
>
>> Shouldn't this be:
>>
>> err = -EFAULT;
>> if (copy_safe_from_sockptr(&opt, sizeof(opt), optval, optlen))
>> break;
>
>
>
