On 64-bit systems sizeof(struct ifreq) is 8 bytes larger than
sizeof(struct iwreq).
For GET calls, the wireless extension code copies back into userspace
using sizeof(struct ifreq) but userspace and elsewhere only allocates
a "struct iwreq". Thus, this copy writes past the end of the iwreq
object and corrupts whatever sits after it in memory.
Fix the copy_to_user() length.
This particularly hurts the compat case because the wireless compat
code uses compat_alloc_userspace() and right after this allocated
buffer is the current bottom of the user stack, and that's what gets
overwritten by the copy_to_user() call.
Signed-off-by: David S. Miller <davem@davemloft.net>
0a06ea8718