[PATCH ver.2] gtp: fix use-after-free and null-ptr-deref in gtp_genl_dump_pdp()

From: Vasiliy Kovalev kovalev@altlinux.org

The gtp_net_ops pernet operations structure for the subsystem must be registered before registering the generic netlink family.

Syzkaller hit 'general protection fault in gtp_genl_dump_pdp' bug:

general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] CPU: 1 PID: 5826 Comm: gtp Not tainted 6.8.0-rc3-std-def-alt1 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-alt1 04/01/2014 RIP: 0010:gtp_genl_dump_pdp+0x1be/0x800 [gtp] Code: c6 89 c6 e8 64 e9 86 df 58 45 85 f6 0f 85 4e 04 00 00 e8 c5 ee 86 df 48 8b 54 24 18 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 de 05 00 00 48 8b 44 24 18 4c 8b 30 4c 39 f0 74 RSP: 0018:ffff888014107220 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff88800fcda588 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f1be4eb05c0(0000) GS:ffff88806ce80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1be4e766cf CR3: 000000000c33e000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: <TASK> ? show_regs+0x90/0xa0 ? die_addr+0x50/0xd0 ? exc_general_protection+0x148/0x220 ? asm_exc_general_protection+0x22/0x30 ? gtp_genl_dump_pdp+0x1be/0x800 [gtp] ? __alloc_skb+0x1dd/0x350 ? __pfx___alloc_skb+0x10/0x10 genl_dumpit+0x11d/0x230 netlink_dump+0x5b9/0xce0 ? lockdep_hardirqs_on_prepare+0x253/0x430 ? __pfx_netlink_dump+0x10/0x10 ? kasan_save_track+0x10/0x40 ? __kasan_kmalloc+0x9b/0xa0 ? genl_start+0x675/0x970 __netlink_dump_start+0x6fc/0x9f0 genl_family_rcv_msg_dumpit+0x1bb/0x2d0 ? __pfx_genl_family_rcv_msg_dumpit+0x10/0x10 ? genl_op_from_small+0x2a/0x440 ? cap_capable+0x1d0/0x240 ? __pfx_genl_start+0x10/0x10 ? __pfx_genl_dumpit+0x10/0x10 ? __pfx_genl_done+0x10/0x10 ? security_capable+0x9d/0xe0

Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)") Cc: stable@vger.kernel.org Signed-off-by: Vasiliy Kovalev kovalev@altlinux.org --- drivers/net/gtp.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index b1919278e931f4..2129ae42c70304 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -1907,20 +1907,20 @@ static int __init gtp_init(void) if (err < 0) goto error_out;

- err = genl_register_family(&gtp_genl_family); + err = register_pernet_subsys(&gtp_net_ops); if (err < 0) goto unreg_rtnl_link;

- err = register_pernet_subsys(&gtp_net_ops); + err = genl_register_family(&gtp_genl_family); if (err < 0) - goto unreg_genl_family; + goto unreg_pernet_subsys;

pr_info("GTP module loaded (pdp ctx size %zd bytes)\n", sizeof(struct pdp_ctx)); return 0;

-unreg_genl_family: - genl_unregister_family(&gtp_genl_family); +unreg_pernet_subsys: + unregister_pernet_subsys(&gtp_net_ops); unreg_rtnl_link: rtnl_link_unregister(&gtp_link_ops); error_out: