target/linux/generic/backport-6.1/796-v6.8-ipmr-fix-kernel-panic-when-forwarding-mcast-packets.patch

   1 From e622502c310f1069fd9f41cd38210553115f610a Mon Sep 17 00:00:00 2001
   2 From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
   3 Date: Thu, 25 Jan 2024 15:18:47 +0100
   4 Subject: [PATCH] ipmr: fix kernel panic when forwarding mcast packets
   5
   6 The stacktrace was:
   7 [   86.305548] BUG: kernel NULL pointer dereference, address: 0000000000000092
   8 [   86.306815] #PF: supervisor read access in kernel mode
   9 [   86.307717] #PF: error_code(0x0000) - not-present page
  10 [   86.308624] PGD 0 P4D 0
  11 [   86.309091] Oops: 0000 [#1] PREEMPT SMP NOPTI
  12 [   86.309883] CPU: 2 PID: 3139 Comm: pimd Tainted: G     U             6.8.0-6wind-knet #1
  13 [   86.311027] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.1-0-g0551a4be2c-prebuilt.qemu-project.org 04/01/2014
  14 [   86.312728] RIP: 0010:ip_mr_forward (/build/work/knet/net/ipv4/ipmr.c:1985)
  15 [ 86.313399] Code: f9 1f 0f 87 85 03 00 00 48 8d 04 5b 48 8d 04 83 49 8d 44 c5 00 48 8b 40 70 48 39 c2 0f 84 d9 00 00 00 49 8b 46 58 48 83 e0 fe <80> b8 92 00 00 00 00 0f 84 55 ff ff ff 49 83 47 38 01 45 85 e4 0f
  16 [   86.316565] RSP: 0018:ffffad21c0583ae0 EFLAGS: 00010246
  17 [   86.317497] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
  18 [   86.318596] RDX: ffff9559cb46c000 RSI: 0000000000000000 RDI: 0000000000000000
  19 [   86.319627] RBP: ffffad21c0583b30 R08: 0000000000000000 R09: 0000000000000000
  20 [   86.320650] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
  21 [   86.321672] R13: ffff9559c093a000 R14: ffff9559cc00b800 R15: ffff9559c09c1d80
  22 [   86.322873] FS:  00007f85db661980(0000) GS:ffff955a79d00000(0000) knlGS:0000000000000000
  23 [   86.324291] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  24 [   86.325314] CR2: 0000000000000092 CR3: 000000002f13a000 CR4: 0000000000350ef0
  25 [   86.326589] Call Trace:
  26 [   86.327036]  <TASK>
  27 [   86.327434] ? show_regs (/build/work/knet/arch/x86/kernel/dumpstack.c:479)
  28 [   86.328049] ? __die (/build/work/knet/arch/x86/kernel/dumpstack.c:421 /build/work/knet/arch/x86/kernel/dumpstack.c:434)
  29 [   86.328508] ? page_fault_oops (/build/work/knet/arch/x86/mm/fault.c:707)
  30 [   86.329107] ? do_user_addr_fault (/build/work/knet/arch/x86/mm/fault.c:1264)
  31 [   86.329756] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
  32 [   86.330350] ? __irq_work_queue_local (/build/work/knet/kernel/irq_work.c:111 (discriminator 1))
  33 [   86.331013] ? exc_page_fault (/build/work/knet/./arch/x86/include/asm/paravirt.h:693 /build/work/knet/arch/x86/mm/fault.c:1515 /build/work/knet/arch/x86/mm/fault.c:1563)
  34 [   86.331702] ? asm_exc_page_fault (/build/work/knet/./arch/x86/include/asm/idtentry.h:570)
  35 [   86.332468] ? ip_mr_forward (/build/work/knet/net/ipv4/ipmr.c:1985)
  36 [   86.333183] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
  37 [   86.333920] ipmr_mfc_add (/build/work/knet/./include/linux/rcupdate.h:782 /build/work/knet/net/ipv4/ipmr.c:1009 /build/work/knet/net/ipv4/ipmr.c:1273)
  38 [   86.334583] ? __pfx_ipmr_hash_cmp (/build/work/knet/net/ipv4/ipmr.c:363)
  39 [   86.335357] ip_mroute_setsockopt (/build/work/knet/net/ipv4/ipmr.c:1470)
  40 [   86.336135] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
  41 [   86.336854] ? ip_mroute_setsockopt (/build/work/knet/net/ipv4/ipmr.c:1470)
  42 [   86.337679] do_ip_setsockopt (/build/work/knet/net/ipv4/ip_sockglue.c:944)
  43 [   86.338408] ? __pfx_unix_stream_read_actor (/build/work/knet/net/unix/af_unix.c:2862)
  44 [   86.339232] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
  45 [   86.339809] ? aa_sk_perm (/build/work/knet/security/apparmor/include/cred.h:153 /build/work/knet/security/apparmor/net.c:181)
  46 [   86.340342] ip_setsockopt (/build/work/knet/net/ipv4/ip_sockglue.c:1415)
  47 [   86.340859] raw_setsockopt (/build/work/knet/net/ipv4/raw.c:836)
  48 [   86.341408] ? security_socket_setsockopt (/build/work/knet/security/security.c:4561 (discriminator 13))
  49 [   86.342116] sock_common_setsockopt (/build/work/knet/net/core/sock.c:3716)
  50 [   86.342747] do_sock_setsockopt (/build/work/knet/net/socket.c:2313)
  51 [   86.343363] __sys_setsockopt (/build/work/knet/./include/linux/file.h:32 /build/work/knet/net/socket.c:2336)
  52 [   86.344020] __x64_sys_setsockopt (/build/work/knet/net/socket.c:2340)
  53 [   86.344766] do_syscall_64 (/build/work/knet/arch/x86/entry/common.c:52 /build/work/knet/arch/x86/entry/common.c:83)
  54 [   86.345433] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
  55 [   86.346161] ? syscall_exit_work (/build/work/knet/./include/linux/audit.h:357 /build/work/knet/kernel/entry/common.c:160)
  56 [   86.346938] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
  57 [   86.347657] ? syscall_exit_to_user_mode (/build/work/knet/kernel/entry/common.c:215)
  58 [   86.348538] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
  59 [   86.349262] ? do_syscall_64 (/build/work/knet/./arch/x86/include/asm/cpufeature.h:171 /build/work/knet/arch/x86/entry/common.c:98)
  60 [   86.349971] entry_SYSCALL_64_after_hwframe (/build/work/knet/arch/x86/entry/entry_64.S:129)
  61
  62 The original packet in ipmr_cache_report() may be queued and then forwarded
  63 with ip_mr_forward(). This last function has the assumption that the skb
  64 dst is set.
  65
  66 After the below commit, the skb dst is dropped by ipv4_pktinfo_prepare(),
  67 which causes the oops.
  68
  69 Fixes: bb7403655b3c ("ipmr: support IP_PKTINFO on cache report IGMP msg")
  70 Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
  71 Reviewed-by: Eric Dumazet <edumazet@google.com>
  72 Link: https://lore.kernel.org/r/20240125141847.1931933-1-nicolas.dichtel@6wind.com
  73 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
  74 ---
  75  include/net/ip.h       | 2 +-
  76  net/ipv4/ip_sockglue.c | 6 ++++--
  77  net/ipv4/ipmr.c        | 2 +-
  78  net/ipv4/raw.c         | 2 +-
  79  net/ipv4/udp.c         | 2 +-
  80  5 files changed, 8 insertions(+), 6 deletions(-)
  81
  82 --- a/include/net/ip.h
  83 +++ b/include/net/ip.h
  84 @@ -752,7 +752,7 @@ int ip_options_rcv_srr(struct sk_buff *s
  85   *     Functions provided by ip_sockglue.c
  86   */
  87
  88 -void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb);
  89 +void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb, bool drop_dst);
  90  void ip_cmsg_recv_offset(struct msghdr *msg, struct sock *sk,
  91                          struct sk_buff *skb, int tlen, int offset);
  92  int ip_cmsg_send(struct sock *sk, struct msghdr *msg,
  93 --- a/net/ipv4/ip_sockglue.c
  94 +++ b/net/ipv4/ip_sockglue.c
  95 @@ -1406,12 +1406,13 @@ e_inval:
  96   * ipv4_pktinfo_prepare - transfer some info from rtable to skb
  97   * @sk: socket
  98   * @skb: buffer
  99 + * @drop_dst: if true, drops skb dst
 100   *
 101   * To support IP_CMSG_PKTINFO option, we store rt_iif and specific
 102   * destination in skb->cb[] before dst drop.
 103   * This way, receiver doesn't make cache line misses to read rtable.
 104   */
 105 -void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
 106 +void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb, bool drop_dst)
 107  {
 108         struct in_pktinfo *pktinfo = PKTINFO_SKB_CB(skb);
 109         bool prepare = (inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO) ||
 110 @@ -1440,7 +1441,8 @@ void ipv4_pktinfo_prepare(const struct s
 111                 pktinfo->ipi_ifindex = 0;
 112                 pktinfo->ipi_spec_dst.s_addr = 0;
 113         }
 114 -       skb_dst_drop(skb);
 115 +       if (drop_dst)
 116 +               skb_dst_drop(skb);
 117  }
 118
 119  int ip_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
 120 --- a/net/ipv4/ipmr.c
 121 +++ b/net/ipv4/ipmr.c
 122 @@ -1073,7 +1073,7 @@ static int ipmr_cache_report(const struc
 123                 msg = (struct igmpmsg *)skb_network_header(skb);
 124                 msg->im_vif = vifi;
 125                 msg->im_vif_hi = vifi >> 8;
 126 -               ipv4_pktinfo_prepare(mroute_sk, pkt);
 127 +               ipv4_pktinfo_prepare(mroute_sk, pkt, false);
 128                 memcpy(skb->cb, pkt->cb, sizeof(skb->cb));
 129                 /* Add our header */
 130                 igmp = skb_put(skb, sizeof(struct igmphdr));
 131 --- a/net/ipv4/raw.c
 132 +++ b/net/ipv4/raw.c
 133 @@ -288,7 +288,7 @@ static int raw_rcv_skb(struct sock *sk,
 134  {
 135         /* Charge it to the socket. */
 136
 137 -       ipv4_pktinfo_prepare(sk, skb);
 138 +       ipv4_pktinfo_prepare(sk, skb, true);
 139         if (sock_queue_rcv_skb(sk, skb) < 0) {
 140                 kfree_skb(skb);
 141                 return NET_RX_DROP;
 142 --- a/net/ipv4/udp.c
 143 +++ b/net/ipv4/udp.c
 144 @@ -2196,7 +2196,7 @@ static int udp_queue_rcv_one_skb(struct
 145
 146         udp_csum_pull_header(skb);
 147
 148 -       ipv4_pktinfo_prepare(sk, skb);
 149 +       ipv4_pktinfo_prepare(sk, skb, true);
 150         return __udp_queue_rcv_skb(sk, skb);
 151
 152  csum_error: