• Arnd Bergmann's avatar
    compat_ioctl: pppoe: fix PPPOEIOCSFWD handling · 055d8824
    Arnd Bergmann authored
    Support for handling the PPPOEIOCSFWD ioctl in compat mode was added in
    linux-2.5.69 along with hundreds of other commands, but was always broken
    sincen only the structure is compatible, but the command number is not,
    due to the size being sizeof(size_t), or at first sizeof(sizeof((struct
    sockaddr_pppox)), which is different on 64-bit architectures.
    
    Guillaume Nault adds:
    
      And the implementation was broken until 2016 (see 29e73269 ("pppoe:
      fix reference counting in PPPoE proxy")), and nobody ever noticed. I
      should probably have removed this ioctl entirely instead of fixing it.
      Clearly, it has never been used.
    
    Fix it by adding a compat_ioctl handler for all pppoe variants that
    translates the command number and then calls the regular ioctl function.
    
    All other ioctl commands handled by pppoe are compatible between 32-bit
    and 64-bit, and require compat_ptr() conversion.
    
    This should apply to all stable kernels.
    Acked-by: default avatarGuillaume Nault <g.nault@alphalink.fr>
    Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    055d8824
pppox.c 3.44 KB