5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 75475bb51e78a3f54ad2f69380f2a1c985e85f2d ]
If fib6_find_prefix() returns NULL, we should silently fallback using fib6_null_entry regardless of RT6_DEBUG value.
syzbot reported:
WARNING: CPU: 0 PID: 5477 at net/ipv6/ip6_fib.c:1516 fib6_add+0x310d/0x3fa0 net/ipv6/ip6_fib.c:1516 Modules linked in: CPU: 0 PID: 5477 Comm: syz-executor.0 Not tainted 6.7.0-rc2-syzkaller-00029-g9b6de136b5f0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023 RIP: 0010:fib6_add+0x310d/0x3fa0 net/ipv6/ip6_fib.c:1516 Code: 00 48 8b 54 24 68 e8 42 22 00 00 48 85 c0 74 14 49 89 c6 e8 d5 d3 c2 f7 eb 5d e8 ce d3 c2 f7 e9 ca 00 00 00 e8 c4 d3 c2 f7 90 <0f> 0b 90 48 b8 00 00 00 00 00 fc ff df 48 8b 4c 24 38 80 3c 01 00 RSP: 0018:ffffc90005067740 EFLAGS: 00010293 RAX: ffffffff89cba5bc RBX: ffffc90005067ab0 RCX: ffff88801a2e9dc0 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90005067980 R08: ffffffff89cbca85 R09: 1ffff110040d4b85 R10: dffffc0000000000 R11: ffffed10040d4b86 R12: 00000000ffffffff R13: 1ffff110051c3904 R14: ffff8880206a5c00 R15: ffff888028e1c820 FS: 00007f763783c6c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f763783bff8 CR3: 000000007f74d000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> __ip6_ins_rt net/ipv6/route.c:1303 [inline] ip6_route_add+0x88/0x120 net/ipv6/route.c:3847 ipv6_route_ioctl+0x525/0x7b0 net/ipv6/route.c:4467 inet6_ioctl+0x21a/0x270 net/ipv6/af_inet6.c:575 sock_do_ioctl+0x152/0x460 net/socket.c:1220 sock_ioctl+0x615/0x8c0 net/socket.c:1339 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x45/0x110 arch/x86/entry/common.c:82
Fixes: 7bbfe00e0252 ("ipv6: fix general protection fault in fib6_add()") Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Cc: Wei Wang weiwan@google.com Reviewed-by: David Ahern dsahern@kernel.org Link: https://lore.kernel.org/r/20231129160630.3509216-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/ip6_fib.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index ef55489651f87..d74a825c50f0c 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -1433,13 +1433,9 @@ int fib6_add(struct fib6_node *root, struct fib6_info *rt, if (!pn_leaf && !(pn->fn_flags & RTN_RTINFO)) { pn_leaf = fib6_find_prefix(info->nl_net, table, pn); -#if RT6_DEBUG >= 2 - if (!pn_leaf) { - WARN_ON(!pn_leaf); + if (!pn_leaf) pn_leaf = info->nl_net->ipv6.fib6_null_entry; - } -#endif fib6_info_hold(pn_leaf); rcu_assign_pointer(pn->leaf, pn_leaf); }