{"cve":"CVE-2024-56674","nvd":{"published":"2024-12-27T15:15:27.313","modified":"2026-06-17T08:12:43.050","status":"Modified","description":"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 <0f> 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 <IRQ>\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 </IRQ>\n <TASK>\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---","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-672"],"references":["https://git.kernel.org/stable/c/3ddccbefebdbe0c4c72a248676e4d39ac66a8e26","https://git.kernel.org/stable/c/b4294d4ac61fbb382811a1d64eaf81f446ce2af4"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:57:56.913276502+00:00"},"epss":{"cve":"CVE-2024-56674","score":0.00201,"percentile":0.10041,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}