CVE-2022-50062

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

net: bgmac: Fix a BUG triggered by wrong bytes_compl

On one of our machines we got:

kernel BUG at lib/dynamic_queue_limits.c:27! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM CPU: 0 PID: 1166 Comm: irq/41-bgmac Tainted: G W O 4.14.275-rt132 #1 Hardware name: BRCM XGS iProc task: ee3415c0 task.stack: ee32a000 PC is at dql_completed+0x168/0x178 LR is at bgmac_poll+0x18c/0x6d8 pc : [] lr : [] psr: 800a0313 sp : ee32be14 ip : 000005ea fp : 00000bd4 r10: ee558500 r9 : c0116298 r8 : 00000002 r7 : 00000000 r6 : ef128810 r5 : 01993267 r4 : 01993851 r3 : ee558000 r2 : 000070e1 r1 : 00000bd4 r0 : ee52c180 Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 12c5387d Table: 8e88c04a DAC: 00000051 Process irq/41-bgmac (pid: 1166, stack limit = 0xee32a210) Stack: (0xee32be14 to 0xee32c000) be00: ee558520 ee52c100 ef128810 be20: 00000000 00000002 c0116298 c04b5a18 00000000 c0a0c8c4 c0951780 00000040 be40: c0701780 ee558500 ee55d520 ef05b340 ef6f9780 ee558520 00000001 00000040 be60: ffffe000 c0a56878 ef6fa040 c0952040 0000012c c0528744 ef6f97b0 fffcfb6a be80: c0a04104 2eda8000 c0a0c4ec c0a0d368 ee32bf44 c0153534 ee32be98 ee32be98 bea0: ee32bea0 ee32bea0 ee32bea8 ee32bea8 00000000 c01462e4 ffffe000 ef6f22a8 bec0: ffffe000 00000008 ee32bee4 c0147430 ffffe000 c094a2a8 00000003 ffffe000 bee0: c0a54528 00208040 0000000c c0a0c8c4 c0a65980 c0124d3c 00000008 ee558520 bf00: c094a23c c0a02080 00000000 c07a9910 ef136970 ef136970 ee30a440 ef136900 bf20: ee30a440 00000001 ef136900 ee30a440 c016d990 00000000 c0108db0 c012500c bf40: ef136900 c016da14 ee30a464 ffffe000 00000001 c016dd14 00000000 c016db28 bf60: ffffe000 ee21a080 ee30a400 00000000 ee32a000 ee30a440 c016dbfc ee25fd70 bf80: ee21a09c c013edcc ee32a000 ee30a400 c013ec7c 00000000 00000000 00000000 bfa0: 00000000 00000000 00000000 c0108470 00000000 00000000 00000000 00000000 bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000 [] (dql_completed) from [] (bgmac_poll+0x18c/0x6d8) [] (bgmac_poll) from [] (net_rx_action+0x1c4/0x494) [] (net_rx_action) from [] (do_current_softirqs+0x1ec/0x43c) [] (do_current_softirqs) from [] (__local_bh_enable+0x80/0x98) [] (__local_bh_enable) from [] (irq_forced_thread_fn+0x84/0x98) [] (irq_forced_thread_fn) from [] (irq_thread+0x118/0x1c0) [] (irq_thread) from [] (kthread+0x150/0x158) [] (kthread) from [] (ret_from_fork+0x14/0x24) Code: a83f15e0 0200001a 0630a0e1 c3ffffea (f201f0e7)

The issue seems similar to commit 90b3b339364c (net: hisilicon: Fix a BUG trigered by wrong bytes_compl) and potentially introduced by commit b38c83dd0866 (bgmac: simplify tx ring index handling).

If there is an RX interrupt between setting ring->end and netdev_sent_queue() we can hit the BUG_ON as bgmac_dma_tx_free() can miscalculate the queue size while called from bgmac_poll().

The machine which triggered the BUG runs a v4.14 RT kernel - but the issue seems present in mainline too.

Affected Software

References

• https://git.kernel.org/stable/c/1b7680c6c1f6de9904f1d9b05c952f0c64a03350
• https://git.kernel.org/stable/c/ab2b55bb25db289ba0b68e3d58494476bdb1041d
• https://git.kernel.org/stable/c/ac6d4482f29ab992b605c1b4bd1347f1f679f4e4
• https://git.kernel.org/stable/c/c506c9a97120f43257e9b3ce7b1f9a24eafc3787
• https://git.kernel.org/stable/c/da1421a29d3b8681ba6a7f686bd0b40dda5acaf3