From 0a5c8b2c8ccbd5987f5d05c6ad6740cdb2e467e8 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 7 Mar 2025 07:43:02 +0000 Subject: [PATCH] bpf: fix a possible NULL deref in bpf_map_offload_map_alloc() Call bpf_dev_offload_check() before netdev_lock_ops(). This is needed if attr->map_ifindex is not valid. Oops: general protection fault, probably for non-canonical address 0xdffffc0000000197: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000cb8-0x0000000000000cbf] RIP: 0010:netdev_need_ops_lock include/linux/netdevice.h:2792 [inline] RIP: 0010:netdev_lock_ops include/linux/netdevice.h:2803 [inline] RIP: 0010:bpf_map_offload_map_alloc+0x19a/0x910 kernel/bpf/offload.c:533 Call Trace: map_create+0x946/0x11c0 kernel/bpf/syscall.c:1455 __sys_bpf+0x6d3/0x820 kernel/bpf/syscall.c:5777 __do_sys_bpf kernel/bpf/syscall.c:5902 [inline] __se_sys_bpf kernel/bpf/syscall.c:5900 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5900 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 Fixes: 97246d6d21c2 ("net: hold netdev instance lock during ndo_bpf") Reported-by: syzbot+0c7bfd8cf3aecec92708@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/67caa2b1.050a0220.15b4b9.0077.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250307074303.1497911-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- kernel/bpf/offload.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index a10153c3be2d..4f707cfe7f10 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -530,11 +530,12 @@ struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr) bpf_map_init_from_attr(&offmap->map, attr); rtnl_lock(); offmap->netdev = __dev_get_by_index(net, attr->map_ifindex); - netdev_lock_ops(offmap->netdev); - down_write(&bpf_devs_lock); err = bpf_dev_offload_check(offmap->netdev); if (err) - goto err_unlock; + goto err_unlock_rtnl; + + netdev_lock_ops(offmap->netdev); + down_write(&bpf_devs_lock); ondev = bpf_offload_find_netdev(offmap->netdev); if (!ondev) { @@ -556,6 +557,7 @@ struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr) err_unlock: up_write(&bpf_devs_lock); netdev_unlock_ops(offmap->netdev); +err_unlock_rtnl: rtnl_unlock(); bpf_map_area_free(offmap); return ERR_PTR(err); -- 2.50.1