Re: [PATCH net] net: sctp: fix sctp_connectx abi for ia32 emulation/compat mode

[Vlad Yasevich <vyasevich@gmail.com>]

On 02/17/2014 06:11 AM, Daniel Borkmann wrote:
> SCTP's sctp_connectx() abi breaks for 64bit kernels compiled with 32bit
> emulation (e.g. ia32 emulation or x86_x32). Due to internal usage of
> 'struct sctp_getaddrs_old' which includes a struct sockaddr pointer,
> sizeof(param) check will always fail in kernel as the structure in
> 64bit kernel space is 4bytes larger than for user binaries compiled
> in 32bit mode. Thus, applications making use of sctp_connectx() won't
> be able to run under such circumstances.
> 
> Introduce a compat interface in the kernel to deal with such
> situations by using a 'struct compat_sctp_getaddrs_old' structure
> where user data is copied into it, and then sucessively transformed
> into a 'struct sctp_getaddrs_old' structure with the help of
> compat_ptr(). That fixes sctp_connectx() abi without any changes
> needed in user space, and lets the SCTP test suite pass when compiled
> in 32bit and run on 64bit kernels.
> 
> Fixes: f9c67811ebc0 ("sctp: Fix regression introduced by new sctp_connectx api")
> Signed-off-by: Daniel Borkmann <dborkman@redhat.com>

Acked-by: Vlad Yasevich <vyasevich@gmail.com>

-vlad