CVE-2024-40960

In the Linux kernel, the following vulnerability has been resolved:

ipv6: prevent possible NULL dereference in rt6_probe()

syzbot caught a NULL dereference in rt6_probe() [1]

Bail out if __in6devget() returns NULL.

[1] Oops: general protection fault, probably for non-canonical address 0xdffffc00000000cb: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000658-0x000000000000065f] CPU: 1 PID: 22444 Comm: syz-executor.0 Not tainted 6.10.0-rc2-syzkaller-00383-gb8481381d4e2 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 RIP: 0010:rt6probe net/ipv6/route.c:656 [inline] RIP: 0010:findmatch+0x8c4/0xf50 net/ipv6/route.c:758 Code: 14 fd f7 48 8b 85 38 ff ff ff 48 c7 45 b0 00 00 00 00 48 8d b8 5c 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 19 RSP: 0018:ffffc900034af070 EFLAGS: 00010203 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90004521000 RDX: 00000000000000cb RSI: ffffffff8990d0cd RDI: 000000000000065c RBP: ffffc900034af150 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000002 R12: 000000000000000a R13: 1ffff92000695e18 R14: ffff8880244a1d20 R15: 0000000000000000 FS: 00007f4844a5a6c0(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b31b27000 CR3: 000000002d42c000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> rt6nhfindmatch+0xfa/0x1a0 net/ipv6/route.c:784 nexthopforeachfib6_nh+0x26d/0x4a0 net/ipv4/nexthop.c:1496 __findrrleaf+0x6e7/0xe00 net/ipv6/route.c:825 findrrleaf net/ipv6/route.c:853 [inline] rt6select net/ipv6/route.c:897 [inline] fib6tablelookup+0x57e/0xa30 net/ipv6/route.c:2195 ip6polroute+0x1cd/0x1150 net/ipv6/route.c:2231 pollookupfunc include/net/ip6fib.h:616 [inline] fib6rulelookup+0x386/0x720 net/ipv6/fib6rules.c:121 ip6routeoutputflagsnoref net/ipv6/route.c:2639 [inline] ip6routeoutputflags+0x1d0/0x640 net/ipv6/route.c:2651 ip6dstlookuptail.constprop.0+0x961/0x1760 net/ipv6/ip6output.c:1147 ip6dstlookupflow+0x99/0x1d0 net/ipv6/ip6output.c:1250 rawv6sendmsg+0xdab/0x4340 net/ipv6/raw.c:898 inetsendmsg+0x119/0x140 net/ipv4/afinet.c:853 socksendmsg_nosec net/socket.c:730 [inline] __socksendmsg net/socket.c:745 [inline] sockwriteiter+0x4b8/0x5c0 net/socket.c:1160 newsyncwrite fs/readwrite.c:497 [inline] vfswrite+0x6b6/0x1140 fs/readwrite.c:590 ksyswrite+0x1f8/0x260 fs/readwrite.c:643 dosyscallx64 arch/x86/entry/common.c:52 [inline] dosyscall64+0xcd/0x250 arch/x86/entry/common.c:83 entrySYSCALL64afterhwframe+0x77/0x7f