b15a38ce95
[ Upstream commit 819be8108fded0b9e710bbbf81193e52f7bab2f7 ]
This patch is to fix a NULL-ptr deref in selinux_socket_connect_helper:
[...] kasan: GPF could be caused by NULL-ptr deref or user memory access
[...] RIP: 0010:selinux_socket_connect_helper+0x94/0x460
[...] Call Trace:
[...] selinux_sctp_bind_connect+0x16a/0x1d0
[...] security_sctp_bind_connect+0x58/0x90
[...] sctp_process_asconf+0xa52/0xfd0 [sctp]
[...] sctp_sf_do_asconf+0x785/0x980 [sctp]
[...] sctp_do_sm+0x175/0x5a0 [sctp]
[...] sctp_assoc_bh_rcv+0x285/0x5b0 [sctp]
[...] sctp_backlog_rcv+0x482/0x910 [sctp]
[...] __release_sock+0x11e/0x310
[...] release_sock+0x4f/0x180
[...] sctp_accept+0x3f9/0x5a0 [sctp]
[...] inet_accept+0xe7/0x720
It was caused by that the 'newsk' sk_socket was not set before going to
security sctp hook when processing asconf chunk with SCTP_PARAM_ADD_IP
or SCTP_PARAM_SET_PRIMARY:
inet_accept()->
sctp_accept():
lock_sock():
lock listening 'sk'
do_softirq():
sctp_rcv(): <-- [1]
asconf chunk arrives and
enqueued in 'sk' backlog
sctp_sock_migrate():
set asoc's sk to 'newsk'
release_sock():
sctp_backlog_rcv():
lock 'newsk'
sctp_process_asconf() <-- [2]
unlock 'newsk'
sock_graft():
set sk_socket <-- [3]
As it shows, at [1] the asconf chunk would be put into the listening 'sk'
backlog, as accept() was holding its sock lock. Then at [2] asconf would
get processed with 'newsk' as asoc's sk had been set to 'newsk'. However,
'newsk' sk_socket is not set until [3], while selinux_sctp_bind_connect()
would deref it, then kernel crashed.
Here to fix it by adding the chunk to sk_backlog until newsk sk_socket is
set when .accept() is done.
Note that sk->sk_socket can be NULL when the sock is closed, so SOCK_DEAD
flag is also needed to check in sctp_newsk_ready().
Thanks to Ondrej for reviewing the code.
Fixes:
|
||
|---|---|---|
| .. | ||
| associola.c | ||
| auth.c | ||
| bind_addr.c | ||
| chunk.c | ||
| debug.c | ||
| diag.c | ||
| endpointola.c | ||
| input.c | ||
| inqueue.c | ||
| ipv6.c | ||
| Kconfig | ||
| Makefile | ||
| objcnt.c | ||
| offload.c | ||
| output.c | ||
| outqueue.c | ||
| primitive.c | ||
| proc.c | ||
| protocol.c | ||
| sm_make_chunk.c | ||
| sm_sideeffect.c | ||
| sm_statefuns.c | ||
| sm_statetable.c | ||
| socket.c | ||
| stream.c | ||
| stream_interleave.c | ||
| stream_sched.c | ||
| stream_sched_prio.c | ||
| stream_sched_rr.c | ||
| sysctl.c | ||
| transport.c | ||
| tsnmap.c | ||
| ulpevent.c | ||
| ulpqueue.c | ||