[SRU][P:linux-azure/N:linux-azure/J:linux-azure][PATCH 0/1] azure: backport "hv_netvsc: Fix panic during namespace deletion with VF"

[Vinicius Peixoto]

BugLink: https://bugs.launchpad.net/bugs/2120803

[Impact]

Microsoft has reported that the following upstream commit:

4c262801ea60 ("hv_netvsc: Fix VF namespace also in synthetic NIC NETDEV_REGISTER event")

introduced a race condition in the hv_netvsc driver that can lead to a
null pointer dereference and subsequent kernel panic during a namespace
change:

[  231.449420] mana 7870:00:00.0 enP30832s1: Moved VF to namespace with: eth0
[  231.449656] BUG: kernel NULL pointer dereference, address: 0000000000000010
[  231.450246] #PF: supervisor read access in kernel mode
[  231.450579] #PF: error_code(0x0000) - not-present page
[  231.450916] PGD 17b8a8067 P4D 0
[  231.451163] Oops: Oops: 0000 [#1] SMP NOPTI
[  231.451450] CPU: 82 UID: 0 PID: 1394 Comm: kworker/u768:1 Not tainted 6.16.0-rc4+ #3 VOLUNTARY
[  231.452042] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 11/21/2024
[  231.452692] Workqueue: netns cleanup_net
[  231.452947] RIP: 0010:default_device_exit_batch+0x16c/0x3f0
[  231.453326] Code: c0 0c f5 b3 e8 d5 db fe ff 48 85 c0 74 15 48 c7 c2 f8 fd ca b2 be 10 00 00 00 48 8d 7d c0 e8 7b 77 25 00 49 8b 86 28 01 00 00 <48> 8b 50 10 4c 8b 2a 4c 8d 62 f0 49 83 ed 10 4c 39 e0 0f 84 d6 00
[  231.454294] RSP: 0018:ff75fc7c9bf9fd00 EFLAGS: 00010246
[  231.454610] RAX: 0000000000000000 RBX: 0000000000000002 RCX: 61c8864680b583eb
[  231.455094] RDX: ff1fa9f71462d800 RSI: ff75fc7c9bf9fd38 RDI: 0000000030766564
[  231.455686] RBP: ff75fc7c9bf9fd78 R08: 0000000000000000 R09: 0000000000000000
[  231.456126] R10: 0000000000000001 R11: 0000000000000004 R12: ff1fa9f70088e340
[  231.456621] R13: ff1fa9f70088e340 R14: ffffffffb3f50c20 R15: ff1fa9f7103e6340
[  231.457161] FS:  0000000000000000(0000) GS:ff1faa6783a08000(0000) knlGS:0000000000000000
[  231.457707] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  231.458031] CR2: 0000000000000010 CR3: 0000000179ab2006 CR4: 0000000000b73ef0
[  231.458434] Call Trace:
[  231.458600]  <TASK>
[  231.458777]  ops_undo_list+0x100/0x220
[  231.459015]  cleanup_net+0x1b8/0x300
[  231.459285]  process_one_work+0x184/0x340

[Fix]

Backport the following upstream fix commit:

33caa208dba6 ("hv_netvsc: Fix panic during namespace deletion with VF")

to the linux-azure trees for all affected releases.

- Plucky, Noble, Jammy: clean cherry-picks
- Focal: simple backport due to a context conflict

[Test plan]

Compile-tested only; Microsoft will perform further validation.

[Where problems could occur]

Any issues here could lead to hangs or crashes during namespace change
operations for NICs within Hyper-V (particularly MANA NICs).

[Other info]
SF #00416493

Haiyang Zhang (1):
  hv_netvsc: Fix panic during namespace deletion with VF

 drivers/net/hyperv/hyperv_net.h |  3 +++
 drivers/net/hyperv/netvsc_drv.c | 29 ++++++++++++++++++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

-- 
2.45.2