ipmr: fix kernel panic when forwarding mcast packets

Bug: https://bugs.gentoo.org/923372

Signed-off-by: Mike Pagano <mpagano@gentoo.org>

2 files changed, 169 insertions, 0 deletions

diff --git a/0000_README b/0000_README
index f27cebb4..94c47ec5 100644
--- a/0000_README
+++ b/0000_README
@@ -119,6 +119,10 @@ Patch:  2000_BT-Check-key-sizes-only-if-Secure-Simple-Pairing-enabled.patch
 From:   https://lore.kernel.org/linux-bluetooth/20190522070540.48895-1-marcel@holtmann.org/raw
 Desc:   Bluetooth: Check key sizes only when Secure Simple Pairing is enabled. See bug #686758
 
+Patch:  2010_ipmr-fix-kern-panic-when-forwarding-mcast-packets.patch
+From:   https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
+Desc:   ipmr: fix kernel panic when forwarding mcast packets
+
 Patch:  2800_amdgpu-Adj-kmalloc-array-calls-for-new-Walloc-size.patch
 From:   sam@gentoo.org
 Desc:   amdgpu: Adjust kmalloc_array calls for new -Walloc-size
diff --git a/2010_ipmr-fix-kern-panic-when-forwarding-mcast-packets.patch b/2010_ipmr-fix-kern-panic-when-forwarding-mcast-packets.patch
new file mode 100644
index 00000000..b8b48252
--- /dev/null
+++ b/2010_ipmr-fix-kern-panic-when-forwarding-mcast-packets.patch
@@ -0,0 +1,165 @@
+From e622502c310f1069fd9f41cd38210553115f610a Mon Sep 17 00:00:00 2001
+From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
+Date: Thu, 25 Jan 2024 15:18:47 +0100
+Subject: ipmr: fix kernel panic when forwarding mcast packets
+
+The stacktrace was:
+[   86.305548] BUG: kernel NULL pointer dereference, address: 0000000000000092
+[   86.306815] #PF: supervisor read access in kernel mode
+[   86.307717] #PF: error_code(0x0000) - not-present page
+[   86.308624] PGD 0 P4D 0
+[   86.309091] Oops: 0000 [#1] PREEMPT SMP NOPTI
+[   86.309883] CPU: 2 PID: 3139 Comm: pimd Tainted: G     U             6.8.0-6wind-knet #1
+[   86.311027] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.1-0-g0551a4be2c-prebuilt.qemu-project.org 04/01/2014
+[   86.312728] RIP: 0010:ip_mr_forward (/build/work/knet/net/ipv4/ipmr.c:1985)
+[ 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
+[   86.316565] RSP: 0018:ffffad21c0583ae0 EFLAGS: 00010246
+[   86.317497] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
+[   86.318596] RDX: ffff9559cb46c000 RSI: 0000000000000000 RDI: 0000000000000000
+[   86.319627] RBP: ffffad21c0583b30 R08: 0000000000000000 R09: 0000000000000000
+[   86.320650] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
+[   86.321672] R13: ffff9559c093a000 R14: ffff9559cc00b800 R15: ffff9559c09c1d80
+[   86.322873] FS:  00007f85db661980(0000) GS:ffff955a79d00000(0000) knlGS:0000000000000000
+[   86.324291] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+[   86.325314] CR2: 0000000000000092 CR3: 000000002f13a000 CR4: 0000000000350ef0
+[   86.326589] Call Trace:
+[   86.327036]  <TASK>
+[   86.327434] ? show_regs (/build/work/knet/arch/x86/kernel/dumpstack.c:479)
+[   86.328049] ? __die (/build/work/knet/arch/x86/kernel/dumpstack.c:421 /build/work/knet/arch/x86/kernel/dumpstack.c:434)
+[   86.328508] ? page_fault_oops (/build/work/knet/arch/x86/mm/fault.c:707)
+[   86.329107] ? do_user_addr_fault (/build/work/knet/arch/x86/mm/fault.c:1264)
+[   86.329756] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
+[   86.330350] ? __irq_work_queue_local (/build/work/knet/kernel/irq_work.c:111 (discriminator 1))
+[   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)
+[   86.331702] ? asm_exc_page_fault (/build/work/knet/./arch/x86/include/asm/idtentry.h:570)
+[   86.332468] ? ip_mr_forward (/build/work/knet/net/ipv4/ipmr.c:1985)
+[   86.333183] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
+[   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)
+[   86.334583] ? __pfx_ipmr_hash_cmp (/build/work/knet/net/ipv4/ipmr.c:363)
+[   86.335357] ip_mroute_setsockopt (/build/work/knet/net/ipv4/ipmr.c:1470)
+[   86.336135] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
+[   86.336854] ? ip_mroute_setsockopt (/build/work/knet/net/ipv4/ipmr.c:1470)
+[   86.337679] do_ip_setsockopt (/build/work/knet/net/ipv4/ip_sockglue.c:944)
+[   86.338408] ? __pfx_unix_stream_read_actor (/build/work/knet/net/unix/af_unix.c:2862)
+[   86.339232] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
+[   86.339809] ? aa_sk_perm (/build/work/knet/security/apparmor/include/cred.h:153 /build/work/knet/security/apparmor/net.c:181)
+[   86.340342] ip_setsockopt (/build/work/knet/net/ipv4/ip_sockglue.c:1415)
+[   86.340859] raw_setsockopt (/build/work/knet/net/ipv4/raw.c:836)
+[   86.341408] ? security_socket_setsockopt (/build/work/knet/security/security.c:4561 (discriminator 13))
+[   86.342116] sock_common_setsockopt (/build/work/knet/net/core/sock.c:3716)
+[   86.342747] do_sock_setsockopt (/build/work/knet/net/socket.c:2313)
+[   86.343363] __sys_setsockopt (/build/work/knet/./include/linux/file.h:32 /build/work/knet/net/socket.c:2336)
+[   86.344020] __x64_sys_setsockopt (/build/work/knet/net/socket.c:2340)
+[   86.344766] do_syscall_64 (/build/work/knet/arch/x86/entry/common.c:52 /build/work/knet/arch/x86/entry/common.c:83)
+[   86.345433] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
+[   86.346161] ? syscall_exit_work (/build/work/knet/./include/linux/audit.h:357 /build/work/knet/kernel/entry/common.c:160)
+[   86.346938] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
+[   86.347657] ? syscall_exit_to_user_mode (/build/work/knet/kernel/entry/common.c:215)
+[   86.348538] ? srso_return_thunk (/build/work/knet/arch/x86/lib/retpoline.S:223)
+[   86.349262] ? do_syscall_64 (/build/work/knet/./arch/x86/include/asm/cpufeature.h:171 /build/work/knet/arch/x86/entry/common.c:98)
+[   86.349971] entry_SYSCALL_64_after_hwframe (/build/work/knet/arch/x86/entry/entry_64.S:129)
+
+The original packet in ipmr_cache_report() may be queued and then forwarded
+with ip_mr_forward(). This last function has the assumption that the skb
+dst is set.
+
+After the below commit, the skb dst is dropped by ipv4_pktinfo_prepare(),
+which causes the oops.
+
+Fixes: bb7403655b3c ("ipmr: support IP_PKTINFO on cache report IGMP msg")
+Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
+Reviewed-by: Eric Dumazet <edumazet@google.com>
+Link: https://lore.kernel.org/r/20240125141847.1931933-1-nicolas.dichtel@6wind.com
+Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+---
+ include/net/ip.h       | 2 +-
+ net/ipv4/ip_sockglue.c | 6 ++++--
+ net/ipv4/ipmr.c        | 2 +-
+ net/ipv4/raw.c         | 2 +-
+ net/ipv4/udp.c         | 2 +-
+ 5 files changed, 8 insertions(+), 6 deletions(-)
+
+diff --git a/include/net/ip.h b/include/net/ip.h
+index de0c69c57e3cb..25cb688bdc623 100644
+--- a/include/net/ip.h
++++ b/include/net/ip.h
+@@ -767,7 +767,7 @@ int ip_options_rcv_srr(struct sk_buff *skb, struct net_device *dev);
+  *	Functions provided by ip_sockglue.c
+  */
+ 
+-void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb);
++void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb, bool drop_dst);
+ void ip_cmsg_recv_offset(struct msghdr *msg, struct sock *sk,
+ 			 struct sk_buff *skb, int tlen, int offset);
+ int ip_cmsg_send(struct sock *sk, struct msghdr *msg,
+diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
+index 7aa9dc0e6760d..21d2ffa919e98 100644
+--- a/net/ipv4/ip_sockglue.c
++++ b/net/ipv4/ip_sockglue.c
+@@ -1363,12 +1363,13 @@ e_inval:
+  * ipv4_pktinfo_prepare - transfer some info from rtable to skb
+  * @sk: socket
+  * @skb: buffer
++ * @drop_dst: if true, drops skb dst
+  *
+  * To support IP_CMSG_PKTINFO option, we store rt_iif and specific
+  * destination in skb->cb[] before dst drop.
+  * This way, receiver doesn't make cache line misses to read rtable.
+  */
+-void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
++void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb, bool drop_dst)
+ {
+ 	struct in_pktinfo *pktinfo = PKTINFO_SKB_CB(skb);
+ 	bool prepare = inet_test_bit(PKTINFO, sk) ||
+@@ -1397,7 +1398,8 @@ void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
+ 		pktinfo->ipi_ifindex = 0;
+ 		pktinfo->ipi_spec_dst.s_addr = 0;
+ 	}
+-	skb_dst_drop(skb);
++	if (drop_dst)
++		skb_dst_drop(skb);
+ }
+ 
+ int ip_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
+diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
+index 9d6f59531b3a0..3622298365105 100644
+--- a/net/ipv4/ipmr.c
++++ b/net/ipv4/ipmr.c
+@@ -1073,7 +1073,7 @@ static int ipmr_cache_report(const struct mr_table *mrt,
+ 		msg = (struct igmpmsg *)skb_network_header(skb);
+ 		msg->im_vif = vifi;
+ 		msg->im_vif_hi = vifi >> 8;
+-		ipv4_pktinfo_prepare(mroute_sk, pkt);
++		ipv4_pktinfo_prepare(mroute_sk, pkt, false);
+ 		memcpy(skb->cb, pkt->cb, sizeof(skb->cb));
+ 		/* Add our header */
+ 		igmp = skb_put(skb, sizeof(struct igmphdr));
+diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
+index 27da9d7294c0b..aea89326c6979 100644
+--- a/net/ipv4/raw.c
++++ b/net/ipv4/raw.c
+@@ -292,7 +292,7 @@ static int raw_rcv_skb(struct sock *sk, struct sk_buff *skb)
+ 
+ 	/* Charge it to the socket. */
+ 
+-	ipv4_pktinfo_prepare(sk, skb);
++	ipv4_pktinfo_prepare(sk, skb, true);
+ 	if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0) {
+ 		kfree_skb_reason(skb, reason);
+ 		return NET_RX_DROP;
+diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
+index 148ffb007969f..f631b0a21af4c 100644
+--- a/net/ipv4/udp.c
++++ b/net/ipv4/udp.c
+@@ -2169,7 +2169,7 @@ static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
+ 
+ 	udp_csum_pull_header(skb);
+ 
+-	ipv4_pktinfo_prepare(sk, skb);
++	ipv4_pktinfo_prepare(sk, skb, true);
+ 	return __udp_queue_rcv_skb(sk, skb);
+ 
+ csum_error:
+-- 
+cgit 1.2.3-korg
+