Hi Jukka,
> The highly optimized TX path for L2CAP channels and its fragmentation
> within the HCI ACL packets requires to copy data from user provided
> IO vectors and also kernel provided memory buffers.
>
> This patch allows channel clients to provide a memcpy_fromiovec callback
> to keep this optimized behavior, but adapt it to kernel vs user memory
> for the TX path. For all kernel internal L2CAP channels, a default
> implementation is provided that can be referenced.
>
> In case of A2MP, this fixes a long-standing issue with wrongly accessing
> kernel memory as user memory.
>
> Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>
> Tested-by: Jukka Rissanen <jukka.rissanen@xxxxxxxxxxxxxxx>
so this patch is bogus as well. This is tough problem to solve :(
reproduce: make C=1 CF=-D__CHECK_ENDIAN__
sparse warnings: (new ones prefixed by >>)
include/net/bluetooth/l2cap.h:870:42: sparse: incorrect type in argument 2 (different address spaces)
include/net/bluetooth/l2cap.h:870:42: expected void const *from
include/net/bluetooth/l2cap.h:870:42: got void [noderef] <asn:1>*iov_base
vim +870 include/net/bluetooth/l2cap.h
854 static inline void l2cap_chan_no_set_shutdown(struct l2cap_chan *chan)
855 {
856 }
857
858 static inline long l2cap_chan_no_get_sndtimeo(struct l2cap_chan *chan)
859 {
860 return 0;
861 }
862
863 static inline int l2cap_chan_no_memcpy_fromiovec(struct l2cap_chan *chan,
864 unsigned char *kdata,
865 struct iovec *iov, int len)
866 {
867 while (len > 0) {
868 if (iov->iov_len) {
869 int copy = min_t(unsigned int, len, iov->iov_len);
>>870 memcpy(kdata, iov->iov_base, copy);
871 len -= copy;
872 kdata += copy;
873 iov->iov_base += copy;
874 iov->iov_len -= copy;
875 }
876 iov++;
877 }
878
The problem is that is that iov_base is defined with __user in linux/uio.h.
struct iovec
{
void __user *iov_base; /* BSD uses caddr_t (1003.1g requires void *) */
__kernel_size_t iov_len; /* Must be size_t (1003.1g) */
};
This means we need to rethink this whole approach once more.
Regards
Marcel
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