Ian reported several skb corruptions triggered by rx-gro-list,
collecting different oops alike:

[   62.624003] BUG: kernel NULL pointer dereference, address: 00000000000000c0
[   62.631083] #PF: supervisor read access in kernel mode
[   62.636312] #PF: error_code(0x0000) - not-present page
[   62.641541] PGD 0 P4D 0
[   62.644174] Oops: 0000 [#1] PREEMPT SMP NOPTI
[   62.648629] CPU: 1 PID: 913 Comm: napi/eno2-79 Not tainted 6.4.0 #364
[   62.655162] Hardware name: Supermicro Super Server/A2SDi-12C-HLN4F, BIOS 1.7a 10/13/2022
[   62.663344] RIP: 0010:__udp_gso_segment (./include/linux/skbuff.h:2858
./include/linux/udp.h:23 net/ipv4/udp_offload.c:228 net/ipv4/udp_offload.c:261
net/ipv4/udp_offload.c:277)
[   62.687193] RSP: 0018:ffffbd3a83b4f868 EFLAGS: 00010246
[   62.692515] RAX: 00000000000000ce RBX: 0000000000000000 RCX: 0000000000000000
[   62.699743] RDX: ffffa124def8a000 RSI: 0000000000000079 RDI: ffffa125952a14d4
[   62.706970] RBP: ffffa124def8a000 R08: 0000000000000022 R09: 00002000001558c9
[   62.714199] R10: 0000000000000000 R11: 00000000be554639 R12: 00000000000000e2
[   62.721426] R13: ffffa125952a1400 R14: ffffa125952a1400 R15: 00002000001558c9
[   62.728654] FS:  0000000000000000(0000) GS:ffffa127efa40000(0000)
knlGS:0000000000000000
[   62.736852] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   62.742702] CR2: 00000000000000c0 CR3: 00000001034b0000 CR4: 00000000003526e0
[   62.749948] Call Trace:
[   62.752498]  <TASK>
[   62.779267] inet_gso_segment (net/ipv4/af_inet.c:1398)
[   62.787605] skb_mac_gso_segment (net/core/gro.c:141)
[   62.791906] __skb_gso_segment (net/core/dev.c:3403 (discriminator 2))
[   62.800492] validate_xmit_skb (./include/linux/netdevice.h:4862
net/core/dev.c:3659)
[   62.804695] validate_xmit_skb_list (net/core/dev.c:3710)
[   62.809158] sch_direct_xmit (net/sched/sch_generic.c:330)
[   62.813198] __dev_queue_xmit (net/core/dev.c:3805 net/core/dev.c:4210)
net/netfilter/core.c:626)
[   62.821093] br_dev_queue_push_xmit (net/bridge/br_forward.c:55)
[   62.825652] maybe_deliver (net/bridge/br_forward.c:193)
[   62.829420] br_flood (net/bridge/br_forward.c:233)
[   62.832758] br_handle_frame_finish (net/bridge/br_input.c:215)
[   62.837403] br_handle_frame (net/bridge/br_input.c:298
net/bridge/br_input.c:416)
[   62.851417] __netif_receive_skb_core.constprop.0 (net/core/dev.c:5387)
[   62.866114] __netif_receive_skb_list_core (net/core/dev.c:5570)
[   62.871367] netif_receive_skb_list_internal (net/core/dev.c:5638
net/core/dev.c:5727)
[   62.876795] napi_complete_done (./include/linux/list.h:37
./include/net/gro.h:434 ./include/net/gro.h:429 net/core/dev.c:6067)
[   62.881004] ixgbe_poll (drivers/net/ethernet/intel/ixgbe/ixgbe_main.c:3191)
[   62.893534] __napi_poll (net/core/dev.c:6498)
[   62.897133] napi_threaded_poll (./include/linux/netpoll.h:89
net/core/dev.c:6640)
[   62.905276] kthread (kernel/kthread.c:379)
[   62.913435] ret_from_fork (arch/x86/entry/entry_64.S:314)
[   62.917119]  </TASK>

In the critical scenario, rx-gro-list GRO-ed packets are fed, via a
bridge, both to the local input path and to an egress device (tun).

The segmentation of such packets unsafely writes to the cloned skbs
with shared heads.

This change addresses the issue by uncloning as needed the
to-be-segmented skbs.

Reported-by: Ian Kumlien <ian.kumlien@gmail.com>
Tested-by: Ian Kumlien <ian.kumlien@gmail.com>
Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Use sendmsg() with MSG_SPLICE_PAGES rather than sendpage in
skb_send_sock().  This causes pages to be spliced from the source iterator
if possible.

This allows ->sendpage() to be replaced by something that can handle
multiple multipage folios in a single transaction.

Note that this could perhaps be improved to fill out a bvec array with all
the frags and then make a single sendmsg call, possibly sticking the header
on the front also.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Link: https://lore.kernel.org/r/20230623225513.2732256-3-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Move declarations into include/net/gso.h and code into net/core/gso.c

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230608191738.3947077-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The "len" variable needs to be signed for the error handling to work
correctly.

Fixes: 2e910b95329c ("net: Add a function to splice pages into an skbuff for MSG_SPLICE_PAGES")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/366861a7-87c8-4bbf-9101-69dd41021d07@kili.mountain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Cross-merge networking fixes after downstream PR.

Conflicts:

net/ipv4/raw.c
  3632679d9e4f ("ipv{4,6}/raw: fix output xfrm lookup wrt protocol")
  c85be08fc4fa ("raw: Stop using RTO_ONLINK.")
https://lore.kernel.org/all/20230525110037.2b532b83@canb.auug.org.au/

Adjacent changes:

drivers/net/ethernet/freescale/fec_main.c
  9025944fddfe ("net: fec: add dma_wmb to ensure correct descriptor values")
  144470c88c5d ("net: fec: using the standard return codes when xdp xmit errors")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Commit 50749f2dd685 ("tcp/udp: Fix memleaks of sk and zerocopy skbs with
TX timestamp.") added a call to skb_orphan_frags_rx() to fix leaks with
zerocopy skbs. But it ended up adding a leak of its own. When
skb_orphan_frags_rx() fails, the function just returns, leaking the skb
it just cloned. Free it before returning.

This bug was discovered and resolved using Coverity Static Analysis
Security Testing (SAST) by Synopsys, Inc.

Fixes: 50749f2dd685 ("tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp.")
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20230522153020.32422-1-ptyadav@amazon.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add a function to handle MSG_SPLICE_PAGES being passed internally to
sendmsg().  Pages are spliced into the given socket buffer if possible and
copied in if not (e.g. they're slab pages or have a zero refcount).

Signed-off-by: David Howells <dhowells@redhat.com>
cc: David Ahern <dsahern@kernel.org>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Pass the maximum number of fragments into skb_append_pagefrags() rather
than using MAX_SKB_FRAGS so that it can be used from code that wants to
specify sysctl_max_skb_frags.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: David Ahern <dsahern@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Most users use __skb_frag_set_page()/skb_frag_off_set()/
skb_frag_size_set() to fill the page desc for a skb frag.

Introduce skb_frag_fill_page_desc() to do that.

net/bpf/test_run.c does not call skb_frag_off_set() to
set the offset, "copy_from_user(page_address(page), ...)"
and 'shinfo' being part of the 'data' kzalloced in
bpf_test_init() suggest that it is assuming offset to be
initialized as zero, so call skb_frag_fill_page_desc()
with offset being zero for this case.

Also, skb_frag_set_page() is not used anymore, so remove
it.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Cross-merge networking fixes. No conflicts.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>