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John Fastabend 5e5dc33d5d bpf: veth driver panics when xdp prog attached before veth_open 
The following panic is observed when bringing up (veth_open) a veth device
that has an XDP program attached.

[   61.519185] kernel BUG at net/core/dev.c:6442!
[   61.519456] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[   61.519752] CPU: 0 PID: 408 Comm: ip Tainted: G        W          6.1.0-rc2-185930-gd9095f92950b-dirty #26
[   61.520288] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
[   61.520806] RIP: 0010:napi_enable+0x3d/0x40
[   61.521077] Code: f6 f6 80 61 08 00 00 02 74 0d 48 83 bf 88 01 00 00 00 74 03 80 cd 01 48 89 d0 f0 48 0f b1 4f 10 48 39 c2 75 c8 c3 cc cc cc cc <0f> 0b 90 48 8b 87 b0 00 00 00 48 81 c7 b0 00 00 00 45 31 c0 48 39
[   61.522226] RSP: 0018:ffffbc9800cc36f8 EFLAGS: 00010246
[   61.522557] RAX: 0000000000000001 RBX: 0000000000000300 RCX: 0000000000000001
[   61.523004] RDX: 0000000000000010 RSI: ffffffff8b0de852 RDI: ffff9f03848e5000
[   61.523452] RBP: 0000000000000000 R08: 0000000000000800 R09: 0000000000000000
[   61.523899] R10: ffff9f0384a96800 R11: ffffffffffa48061 R12: ffff9f03849c3000
[   61.524345] R13: 0000000000000300 R14: ffff9f03848e5000 R15: 0000001000000100
[   61.524792] FS:  00007f58cb64d2c0(0000) GS:ffff9f03bbc00000(0000) knlGS:0000000000000000
[   61.525301] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   61.525673] CR2: 00007f6cc629b498 CR3: 000000010498c000 CR4: 00000000000006f0
[   61.526121] Call Trace:
[   61.526284]  <TASK>
[   61.526425]  __veth_napi_enable_range+0xd6/0x230
[   61.526723]  veth_enable_xdp+0xd0/0x160
[   61.526969]  veth_open+0x2e/0xc0
[   61.527180]  __dev_open+0xe2/0x1b0
[   61.527405]  __dev_change_flags+0x1a1/0x210
[   61.527673]  dev_change_flags+0x1c/0x60

This happens because we are calling veth_napi_enable() on already enabled
queues. The root cause is in commit 2e0de6366a changed the control logic
dropping this case,

        if (priv->_xdp_prog) {
                err = veth_enable_xdp(dev);
                if (err)
                        return err;
-       } else if (veth_gro_requested(dev)) {
+               /* refer to the logic in veth_xdp_set() */
+               if (!rtnl_dereference(peer_rq->napi)) {
+                       err = veth_napi_enable(peer);
+                       if (err)
+                               return err;
+               }

so that now veth_napi_enable is called if the peer has not yet
initialiazed its peer_rq->napi. The issue is this will happen
even if the NIC is not up. Then in veth_enable_xdp just above
we have similar path,

  veth_enable_xdp
   napi_already_on = (dev->flags & IFF_UP) && rcu_access_pointer(rq->napi)
    err = veth_enable_xdp_range(dev, 0, dev->real_num_rx_queues, napi_already_on);

The trouble is an xdp prog is assigned before bringing the device up each
of the veth_open path will enable the peers xdp napi structs. But then when
we bring the peer up it will similar try to enable again because from
veth_open the IFF_UP flag is not set until after the op in __dev_open so
we believe napi_alread_on = false.

To fix this just drop the IFF_UP test and rely on checking if the napi
struct is enabled. This also matches the peer check in veth_xdp for
disabling.

To reproduce run ./test_xdp_meta.sh I found adding Cilium/Tetragon tests
for XDP.

Fixes: 2e0de6366a ("veth: Avoid drop packets when xdp_redirect performs")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20221108221650.808950-2-john.fastabend@gmail.com
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2022-11-09 21:02:24 -08:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-11-03 13:21:54 -07:00
block block-6.1-2022-10-28 2022-10-29 18:06:52 -07:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_bytes() when possible 2022-10-11 17:42:58 -06:00
Documentation Documentation: bpf: Escape underscore in BPF type name prefix 2022-11-04 16:10:07 -07:00
drivers bpf: veth driver panics when xdp prog attached before veth_open 2022-11-09 21:02:24 -08:00
fs NFS Client Bugfixes for Linux 6.1-rc 2022-11-02 11:18:13 -07:00
include bpf: Refactor map->off_arr handling 2022-11-03 23:09:40 -07:00
init init: Kconfig: fix spelling mistake "satify" -> "satisfy" 2022-10-20 21:27:22 -07:00
io_uring io_uring: unlock if __io_run_local_work locked inside 2022-10-27 09:52:12 -06:00
ipc ipc/msg.c: fix percpu_counter use after free 2022-10-28 13:37:22 -07:00
kernel bpf: aggressively forget precise markings during state checkpointing 2022-11-04 11:51:45 -07:00
lib Networking fixes for 6.1-rc4, including fixes from bluetooth and 2022-11-03 10:51:59 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mmap: fix remap_file_pages() regression 2022-10-28 13:37:23 -07:00
net bpf: Consolidate spin_lock, timer management into btf_record 2022-11-03 22:19:40 -07:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples samples/bpf: Fix sockex3 error: Missing BPF prog type 2022-11-07 17:13:35 -08:00
scripts bpf-next-for-netdev 2022-11-02 08:18:27 -07:00
security lsm/stable-6.1 PR 20221031 2022-10-31 12:09:42 -07:00
sound ALSA: aoa: Fix I2S device accounting 2022-10-27 08:53:08 +02:00
tools selftests: Fix test group SKIPPED result 2022-11-09 21:00:22 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Reject attempts to consume or refresh inactive gfn_to_pfn_cache 2022-10-27 06:48:18 -04:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap mailmap: update email for Qais Yousef 2022-10-20 21:27:21 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-11-03 13:21:54 -07:00
Makefile Linux 6.1-rc3 2022-10-30 15:19:28 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.