{"id":"CVE-2024-56674","summary":"virtio_net: correct netdev_tx_reset_queue() invocation point","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nvirtio_net: correct netdev_tx_reset_queue() invocation point\n\nWhen virtnet_close is followed by virtnet_open, some TX completions can\npossibly remain unconsumed, until they are finally processed during the\nfirst NAPI poll after the netdev_tx_reset_queue(), resulting in a crash\n[1]. Commit b96ed2c97c79 (\"virtio_net: move netdev_tx_reset_queue() call\nbefore RX napi enable\") was not sufficient to eliminate all BQL crash\ncases for virtio-net.\n\nThis issue can be reproduced with the latest net-next master by running:\n`while :; do ip l set DEV down; ip l set DEV up; done` under heavy network\nTX load from inside the machine.\n\nnetdev_tx_reset_queue() can actually be dropped from virtnet_open path;\nthe device is not stopped in any case. For BQL core part, it's just like\ntraffic nearly ceases to exist for some period. For stall detector added\nto BQL, even if virtnet_close could somehow lead to some TX completions\ndelayed for long, followed by virtnet_open, we can just take it as stall\nas mentioned in commit 6025b9135f7a (\"net: dqs: add NIC stall detector\nbased on BQL\"). Note also that users can still reset stall_max via sysfs.\n\nSo, drop netdev_tx_reset_queue() from virtnet_enable_queue_pair(). This\neliminates the BQL crashes. As a result, netdev_tx_reset_queue() is now\nexplicitly required in freeze/restore path. This patch adds it to\nimmediately after free_unused_bufs(), following the rule of thumb:\nnetdev_tx_reset_queue() should follow any SKB freeing not followed by\nnetdev_tx_completed_queue(). This seems the most consistent and\nstreamlined approach, and now netdev_tx_reset_queue() runs whenever\nfree_unused_bufs() is done.\n\n[1]:\n------------[ cut here ]------------\nkernel BUG at lib/dynamic_queue_limits.c:99!\nOops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI\nCPU: 7 UID: 0 PID: 1598 Comm: ip Tainted: G    N 6.12.0net-next_main+ #2\nTainted: [N]=TEST\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), \\\nBIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\nRIP: 0010:dql_completed+0x26b/0x290\nCode: b7 c2 49 89 e9 44 89 da 89 c6 4c 89 d7 e8 ed 17 47 00 58 65 ff 0d\n4d 27 90 7e 0f 85 fd fe ff ff e8 ea 53 8d ff e9 f3 fe ff ff \u003c0f\u003e 0b 01\nd2 44 89 d1 29 d1 ba 00 00 00 00 0f 48 ca e9 28 ff ff ff\nRSP: 0018:ffffc900002b0d08 EFLAGS: 00010297\nRAX: 0000000000000000 RBX: ffff888102398c80 RCX: 0000000080190009\nRDX: 0000000000000000 RSI: 000000000000006a RDI: 0000000000000000\nRBP: ffff888102398c00 R08: 0000000000000000 R09: 0000000000000000\nR10: 00000000000000ca R11: 0000000000015681 R12: 0000000000000001\nR13: ffffc900002b0d68 R14: ffff88811115e000 R15: ffff8881107aca40\nFS:  00007f41ded69500(0000) GS:ffff888667dc0000(0000)\nknlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000556ccc2dc1a0 CR3: 0000000104fd8003 CR4: 0000000000772ef0\nPKRU: 55555554\nCall Trace:\n \u003cIRQ\u003e\n ? die+0x32/0x80\n ? do_trap+0xd9/0x100\n ? dql_completed+0x26b/0x290\n ? dql_completed+0x26b/0x290\n ? do_error_trap+0x6d/0xb0\n ? dql_completed+0x26b/0x290\n ? exc_invalid_op+0x4c/0x60\n ? dql_completed+0x26b/0x290\n ? asm_exc_invalid_op+0x16/0x20\n ? dql_completed+0x26b/0x290\n __free_old_xmit+0xff/0x170 [virtio_net]\n free_old_xmit+0x54/0xc0 [virtio_net]\n virtnet_poll+0xf4/0xe30 [virtio_net]\n ? __update_load_avg_cfs_rq+0x264/0x2d0\n ? update_curr+0x35/0x260\n ? reweight_entity+0x1be/0x260\n __napi_poll.constprop.0+0x28/0x1c0\n net_rx_action+0x329/0x420\n ? enqueue_hrtimer+0x35/0x90\n ? trace_hardirqs_on+0x1d/0x80\n ? kvm_sched_clock_read+0xd/0x20\n ? sched_clock+0xc/0x30\n ? kvm_sched_clock_read+0xd/0x20\n ? sched_clock+0xc/0x30\n ? sched_clock_cpu+0xd/0x1a0\n handle_softirqs+0x138/0x3e0\n do_softirq.part.0+0x89/0xc0\n \u003c/IRQ\u003e\n \u003cTASK\u003e\n __local_bh_enable_ip+0xa7/0xb0\n virtnet_open+0xc8/0x310 [virtio_net]\n __dev_open+0xfa/0x1b0\n __dev_change_flags+0x1de/0x250\n dev_change_flags+0x22/0x60\n do_setlink.isra.0+0x2df/0x10b0\n ? rtnetlink_rcv_msg+0x34f/0x3f0\n ? netlink_rcv_skb+0x54/0x100\n ? netlink_unicas\n---truncated---","modified":"2026-04-02T12:25:05.782913Z","published":"2024-12-27T15:06:35.160Z","related":["USN-7276-1","USN-7277-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56674.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/3ddccbefebdbe0c4c72a248676e4d39ac66a8e26"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b4294d4ac61fbb382811a1d64eaf81f446ce2af4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56674.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-56674"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c8bd1f7f3e61fc6c562c806045f3ccd2cc819c01"},{"fixed":"b4294d4ac61fbb382811a1d64eaf81f446ce2af4"},{"fixed":"3ddccbefebdbe0c4c72a248676e4d39ac66a8e26"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-56674.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}