{"id":"CVE-2025-21653","summary":"net_sched: cls_flow: validate TCA_FLOW_RSHIFT attribute","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: cls_flow: validate TCA_FLOW_RSHIFT attribute\n\nsyzbot found that TCA_FLOW_RSHIFT attribute was not validated.\nRight shitfing a 32bit integer is undefined for large shift values.\n\nUBSAN: shift-out-of-bounds in net/sched/cls_flow.c:329:23\nshift exponent 9445 is too large for 32-bit type 'u32' (aka 'unsigned int')\nCPU: 1 UID: 0 PID: 54 Comm: kworker/u8:3 Not tainted 6.13.0-rc3-syzkaller-00180-g4f619d518db9 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\nWorkqueue: ipv6_addrconf addrconf_dad_work\nCall Trace:\n \u003cTASK\u003e\n  __dump_stack lib/dump_stack.c:94 [inline]\n  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120\n  ubsan_epilogue lib/ubsan.c:231 [inline]\n  __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468\n  flow_classify+0x24d5/0x25b0 net/sched/cls_flow.c:329\n  tc_classify include/net/tc_wrapper.h:197 [inline]\n  __tcf_classify net/sched/cls_api.c:1771 [inline]\n  tcf_classify+0x420/0x1160 net/sched/cls_api.c:1867\n  sfb_classify net/sched/sch_sfb.c:260 [inline]\n  sfb_enqueue+0x3ad/0x18b0 net/sched/sch_sfb.c:318\n  dev_qdisc_enqueue+0x4b/0x290 net/core/dev.c:3793\n  __dev_xmit_skb net/core/dev.c:3889 [inline]\n  __dev_queue_xmit+0xf0e/0x3f50 net/core/dev.c:4400\n  dev_queue_xmit include/linux/netdevice.h:3168 [inline]\n  neigh_hh_output include/net/neighbour.h:523 [inline]\n  neigh_output include/net/neighbour.h:537 [inline]\n  ip_finish_output2+0xd41/0x1390 net/ipv4/ip_output.c:236\n  iptunnel_xmit+0x55d/0x9b0 net/ipv4/ip_tunnel_core.c:82\n  udp_tunnel_xmit_skb+0x262/0x3b0 net/ipv4/udp_tunnel_core.c:173\n  geneve_xmit_skb drivers/net/geneve.c:916 [inline]\n  geneve_xmit+0x21dc/0x2d00 drivers/net/geneve.c:1039\n  __netdev_start_xmit include/linux/netdevice.h:5002 [inline]\n  netdev_start_xmit include/linux/netdevice.h:5011 [inline]\n  xmit_one net/core/dev.c:3590 [inline]\n  dev_hard_start_xmit+0x27a/0x7d0 net/core/dev.c:3606\n  __dev_queue_xmit+0x1b73/0x3f50 net/core/dev.c:4434","modified":"2026-04-16T00:07:24.619359983Z","published":"2025-01-19T10:18:10.354Z","related":["SUSE-SU-2025:0428-1","SUSE-SU-2025:0499-1","SUSE-SU-2025:0557-1","SUSE-SU-2025:0564-1","SUSE-SU-2025:0565-1","SUSE-SU-2025:20165-1","SUSE-SU-2025:20166-1","SUSE-SU-2025:20248-1","SUSE-SU-2025:20249-1","USN-7379-2","USN-7380-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21653.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2011749ca96460386844dfc7e0fde53ebee96f3c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/43658e4a5f2770ad94e93362885ff51c10cf3179"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6fde663f7321418996645ee602a473457640542f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9858f4afeb2e59506e714176bd3e135539a3eeec"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a039e54397c6a75b713b9ce7894a62e06956aa92"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a313d6e6d5f3a631cae5a241c392c28868aa5c5e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e54beb9aed2a90dddf4c5d68fcfc9a01f3e40a61"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21653.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21653"},{"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":"e5dfb815181fcb186d6080ac3a091eadff2d98fe"},{"fixed":"9858f4afeb2e59506e714176bd3e135539a3eeec"},{"fixed":"43658e4a5f2770ad94e93362885ff51c10cf3179"},{"fixed":"a313d6e6d5f3a631cae5a241c392c28868aa5c5e"},{"fixed":"2011749ca96460386844dfc7e0fde53ebee96f3c"},{"fixed":"e54beb9aed2a90dddf4c5d68fcfc9a01f3e40a61"},{"fixed":"6fde663f7321418996645ee602a473457640542f"},{"fixed":"a039e54397c6a75b713b9ce7894a62e06956aa92"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21653.json"}}],"schema_version":"1.7.5"}