From: Eric Dumazet edumazet@google.com

stable inclusion from stable-v5.10.221 commit de5ad4d45cd0128a2a37555f48ab69aa19d78adc category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAD0KR CVE: CVE-2024-40961

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

--------------------------------

[ Upstream commit 2eab4543a2204092c3a7af81d7d6c506e59a03a6 ]

syzbot reminds us that in6_dev_get() can return NULL.

fib6_nh_init() ip6_validate_gw( &idev ) ip6_route_check_nh( idev ) *idev = in6_dev_get(dev); // can be NULL

Oops: general protection fault, probably for non-canonical address 0xdffffc00000000bc: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x00000000000005e0-0x00000000000005e7] CPU: 0 PID: 11237 Comm: syz-executor.3 Not tainted 6.10.0-rc2-syzkaller-00249-gbe27b8965297 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 RIP: 0010:fib6_nh_init+0x640/0x2160 net/ipv6/route.c:3606 Code: 00 00 fc ff df 4c 8b 64 24 58 48 8b 44 24 28 4c 8b 74 24 30 48 89 c1 48 89 44 24 28 48 8d 98 e0 05 00 00 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 b3 17 00 00 8b 1b 31 ff 89 de e8 b8 8b RSP: 0018:ffffc900032775a0 EFLAGS: 00010202 RAX: 00000000000000bc RBX: 00000000000005e0 RCX: 0000000000000000 RDX: 0000000000000010 RSI: ffffc90003277a54 RDI: ffff88802b3a08d8 RBP: ffffc900032778b0 R08: 00000000000002fc R09: 0000000000000000 R10: 00000000000002fc R11: 0000000000000000 R12: ffff88802b3a08b8 R13: 1ffff9200064eec8 R14: ffffc90003277a00 R15: dffffc0000000000 FS: 00007f940feb06c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000245e8000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ip6_route_info_create+0x99e/0x12b0 net/ipv6/route.c:3809 ip6_route_add+0x28/0x160 net/ipv6/route.c:3853 ipv6_route_ioctl+0x588/0x870 net/ipv6/route.c:4483 inet6_ioctl+0x21a/0x280 net/ipv6/af_inet6.c:579 sock_do_ioctl+0x158/0x460 net/socket.c:1222 sock_ioctl+0x629/0x8e0 net/socket.c:1341 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f940f07cea9

Fixes: 428604fb118f ("ipv6: do not set routes if disable_ipv6 has been enabled") Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Acked-by: Lorenzo Bianconi lorenzo@kernel.org Reviewed-by: David Ahern dsahern@kernel.org Link: https://lore.kernel.org/r/20240614082002.26407-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Dong Chenchen dongchenchen2@huawei.com --- net/ipv6/route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c index d6e9a543a687..7809905953e7 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -3485,7 +3485,7 @@ int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh, if (!dev) goto out;

- if (idev->cnf.disable_ipv6) { + if (!idev || idev->cnf.disable_ipv6) { NL_SET_ERR_MSG(extack, "IPv6 is disabled on nexthop device"); err = -EACCES; goto out;