876e8ca836
Commit 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.")
introduced UDP listifyed GRO. The segmentation relies on frag_list being
untouched when passing through the network stack. This assumption can be
broken sometimes, where frag_list itself gets pulled into linear area,
leaving frag_list being NULL. When this happens it can trigger
following NULL pointer dereference, and panic the kernel. Reverse the
test condition should fix it.
[19185.577801][ C1] BUG: kernel NULL pointer dereference, address:
...
[19185.663775][ C1] RIP: 0010:skb_segment_list+0x1cc/0x390
...
[19185.834644][ C1] Call Trace:
[19185.841730][ C1] <TASK>
[19185.848563][ C1] __udp_gso_segment+0x33e/0x510
[19185.857370][ C1] inet_gso_segment+0x15b/0x3e0
[19185.866059][ C1] skb_mac_gso_segment+0x97/0x110
[19185.874939][ C1] __skb_gso_segment+0xb2/0x160
[19185.883646][ C1] udp_queue_rcv_skb+0xc3/0x1d0
[19185.892319][ C1] udp_unicast_rcv_skb+0x75/0x90
[19185.900979][ C1] ip_protocol_deliver_rcu+0xd2/0x200
[19185.910003][ C1] ip_local_deliver_finish+0x44/0x60
[19185.918757][ C1] __netif_receive_skb_one_core+0x8b/0xa0
[19185.927834][ C1] process_backlog+0x88/0x130
[19185.935840][ C1] __napi_poll+0x27/0x150
[19185.943447][ C1] net_rx_action+0x27e/0x5f0
[19185.951331][ C1] ? mlx5_cq_tasklet_cb+0x70/0x160 [mlx5_core]
[19185.960848][ C1] __do_softirq+0xbc/0x25d
[19185.968607][ C1] irq_exit_rcu+0x83/0xb0
[19185.976247][ C1] common_interrupt+0x43/0xa0
[19185.984235][ C1] asm_common_interrupt+0x22/0x40
...
[19186.094106][ C1] </TASK>
Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.")
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/Y9gt5EUizK1UImEP@debian
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.