From: Vivien Didelot <vivien.dide...@gmail.com> Date: Mon, 3 Jun 2019 16:57:13 -0400
> ethtool_get_regs() allocates a buffer of size ops->get_regs_len(), > and pass it to the kernel driver via ops->get_regs() for filling. > > There is no restriction about what the kernel drivers can or cannot do > with the open ethtool_regs structure. They usually set regs->version > and ignore regs->len or set it to the same size as ops->get_regs_len(). > > But if userspace allocates a smaller buffer for the registers dump, > we would cause a userspace buffer overflow in the final copy_to_user() > call, which uses the regs.len value potentially reset by the driver. > > To fix this, make this case obvious and store regs.len before calling > ops->get_regs(), to only copy as much data as requested by userspace, > up to the value returned by ops->get_regs_len(). > > While at it, remove the redundant check for non-null regbuf. > > Signed-off-by: Vivien Didelot <vivien.dide...@gmail.com> Applied and queued up for -stable, thanks.
