Vulnerability CVE-2024-39502
Published: 2024-07-12

Description:
In the Linux kernel, the following vulnerability has been resolved:

ionic: fix use after netif_napi_del()

When queues are started, netif_napi_add() and napi_enable() are called.
If there are 4 queues and only 3 queues are used for the current
configuration, only 3 queues' napi should be registered and enabled.
The ionic_qcq_enable() checks whether the .poll pointer is not NULL for
enabling only the using queue' napi. Unused queues' napi will not be
registered by netif_napi_add(), so the .poll pointer indicates NULL.
But it couldn't distinguish whether the napi was unregistered or not
because netif_napi_del() doesn't reset the .poll pointer to NULL.
So, ionic_qcq_enable() calls napi_enable() for the queue, which was
unregistered by netif_napi_del().

Reproducer:
ethtool -L <interface name> rx 1 tx 1 combined 0
ethtool -L <interface name> rx 0 tx 0 combined 1
ethtool -L <interface name> rx 0 tx 0 combined 4

Splat looks like:
kernel BUG at net/core/dev.c:6666!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
CPU: 3 PID: 1057 Comm: kworker/3:3 Not tainted 6.10.0-rc2+ #16
Workqueue: events ionic_lif_deferred_work [ionic]
RIP: 0010:napi_enable+0x3b/0x40
Code: 48 89 c2 48 83 e2 f6 80 b9 61 09 00 00 00 74 0d 48 83 bf 60 01 00 00 00 74 03 80 ce 01 f0 4f
RSP: 0018:ffffb6ed83227d48 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff97560cda0828 RCX: 0000000000000029
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff97560cda0a28
RBP: ffffb6ed83227d50 R08: 0000000000000400 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: ffff97560ce3c1a0 R14: 0000000000000000 R15: ffff975613ba0a20
FS: 0000000000000000(0000) GS:ffff975d5f780000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8f734ee200 CR3: 0000000103e50000 CR4: 00000000007506f0
PKRU: 55555554
Call Trace:
<TASK>
? die+0x33/0x90
? do_trap+0xd9/0x100
? napi_enable+0x3b/0x40
? do_error_trap+0x83/0xb0
? napi_enable+0x3b/0x40
? napi_enable+0x3b/0x40
? exc_invalid_op+0x4e/0x70
? napi_enable+0x3b/0x40
? asm_exc_invalid_op+0x16/0x20
? napi_enable+0x3b/0x40
ionic_qcq_enable+0xb7/0x180 [ionic 59bdfc8a035436e1c4224ff7d10789e3f14643f8]
ionic_start_queues+0xc4/0x290 [ionic 59bdfc8a035436e1c4224ff7d10789e3f14643f8]
ionic_link_status_check+0x11c/0x170 [ionic 59bdfc8a035436e1c4224ff7d10789e3f14643f8]
ionic_lif_deferred_work+0x129/0x280 [ionic 59bdfc8a035436e1c4224ff7d10789e3f14643f8]
process_one_work+0x145/0x360
worker_thread+0x2bb/0x3d0
? __pfx_worker_thread+0x10/0x10
kthread+0xcc/0x100
? __pfx_kthread+0x10/0x10
ret_from_fork+0x2d/0x50
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30

 References:
https://git.kernel.org/stable/c/0d19267cb150e8f76ade210e16ee820a77f684e7
https://git.kernel.org/stable/c/ff9c2a9426ecf5b9631e9fd74993b357262387d6
https://git.kernel.org/stable/c/8edd18dab443863e9e48f084e7f123fca3065e4e
https://git.kernel.org/stable/c/60cd714871cd5a683353a355cbb17a685245cf84
https://git.kernel.org/stable/c/183ebc167a8a19e916b885d4bb61a3491991bfa5
https://git.kernel.org/stable/c/a87d72b37b9ec2c1e18fe36b09241d8b30334a2e
https://git.kernel.org/stable/c/79f18a41dd056115d685f3b0a419c7cd40055e13
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