syzbot


KASAN: slab-out-of-bounds Read in tc_setup_flow_action

Status: upstream: reported C repro on 2025/01/04 22:42
Reported-by: syzbot+7a1c3b8c6950bb246cfc@syzkaller.appspotmail.com
First crash: 505d, last: 12h33m
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: slab-out-of-bounds Read in tc_setup_flow_action origin:lts 17 C 2306 1d08h 505d 0/2 upstream: reported C repro on 2025/01/04 22:41

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in is_tcf_tunnel_set include/net/tc_act/tc_tunnel_key.h:33 [inline]
BUG: KASAN: slab-out-of-bounds in tc_setup_flow_action+0x842/0x32b0 net/sched/cls_api.c:3640
Read of size 8 at addr ffff888110170cc0 by task syz.2.17/369

CPU: 0 PID: 369 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0xe2/0x130 mm/kasan/report.c:452
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
 is_tcf_tunnel_set include/net/tc_act/tc_tunnel_key.h:33 [inline]
 tc_setup_flow_action+0x842/0x32b0 net/sched/cls_api.c:3640
 mall_replace_hw_filter+0x2cc/0x8a0 net/sched/cls_matchall.c:100
 mall_change+0x546/0x760 net/sched/cls_matchall.c:236
 tc_new_tfilter+0x1452/0x1a90 net/sched/cls_api.c:2134
 rtnetlink_rcv_msg+0x845/0xcc0 net/core/rtnetlink.c:5604
 netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2503
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5631
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x876/0xa40 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x89c/0xb50 net/netlink/af_netlink.c:1914
 sock_sendmsg_nosec net/socket.c:652 [inline]
 __sock_sendmsg net/socket.c:664 [inline]
 ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2376
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2430
 __sys_sendmsg net/socket.c:2459 [inline]
 __do_sys_sendmsg net/socket.c:2468 [inline]
 __se_sys_sendmsg net/socket.c:2466 [inline]
 __x64_sys_sendmsg+0x1f9/0x2c0 net/socket.c:2466
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f229322de59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc6f84dea8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f22934a6fa0 RCX: 00007f229322de59
RDX: 0000000020000000 RSI: 0000200000000040 RDI: 0000000000000003
RBP: 00007f22932c3d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f22934a6fac R14: 00007f22934a6fa0 R15: 00007f22934a6fa0

Allocated by task 369:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:430 [inline]
 ____kasan_kmalloc mm/kasan/common.c:509 [inline]
 __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 __kmalloc+0x1a4/0x330 mm/slub.c:4038
 kmalloc include/linux/slab.h:560 [inline]
 kzalloc include/linux/slab.h:667 [inline]
 tcf_idr_create+0x5f/0x790 net/sched/act_api.c:430
 tcf_idr_create_from_flags+0x61/0x70 net/sched/act_api.c:488
 tcf_gact_init+0x2e6/0x560 net/sched/act_gact.c:102
 tcf_action_init_1+0x443/0x6e0 net/sched/act_api.c:1052
 tcf_action_init+0x227/0x780 net/sched/act_api.c:1109
 tcf_exts_validate+0x248/0x570 net/sched/cls_api.c:3087
 mall_set_parms+0x4b/0x410 net/sched/cls_matchall.c:171
 mall_change+0x47a/0x760 net/sched/cls_matchall.c:230
 tc_new_tfilter+0x1452/0x1a90 net/sched/cls_api.c:2134
 rtnetlink_rcv_msg+0x845/0xcc0 net/core/rtnetlink.c:5604
 netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2503
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5631
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x876/0xa40 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x89c/0xb50 net/netlink/af_netlink.c:1914
 sock_sendmsg_nosec net/socket.c:652 [inline]
 __sock_sendmsg net/socket.c:664 [inline]
 ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2376
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2430
 __sys_sendmsg net/socket.c:2459 [inline]
 __do_sys_sendmsg net/socket.c:2468 [inline]
 __se_sys_sendmsg net/socket.c:2466 [inline]
 __x64_sys_sendmsg+0x1f9/0x2c0 net/socket.c:2466
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff888110170c00
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 0 bytes to the right of
 192-byte region [ffff888110170c00, ffff888110170cc0)
The buggy address belongs to the page:
page:ffffea0004405c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x110170
flags: 0x4000000000000200(slab)
raw: 4000000000000200 dead000000000100 dead000000000122 ffff888100043380
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 365, ts 22573613536, free_ts 22573602749
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x179/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x290/0x620 mm/page_alloc.c:5384
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2a6/0x450 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc_trace+0x1b0/0x2e0 mm/slub.c:2977
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:667 [inline]
 kernfs_fop_open+0x343/0xb30 fs/kernfs/file.c:628
 do_dentry_open+0x793/0x1090 fs/open.c:819
 vfs_open+0x73/0x80 fs/open.c:944
 do_open fs/namei.c:3399 [inline]
 path_openat+0x280f/0x31c0 fs/namei.c:3517
 do_filp_open+0x1e2/0x410 fs/namei.c:3544
 do_sys_openat2+0x19f/0x750 fs/open.c:1219
 do_sys_open fs/open.c:1235 [inline]
 __do_sys_openat fs/open.c:1251 [inline]
 __se_sys_openat fs/open.c:1246 [inline]
 __x64_sys_openat+0x136/0x160 fs/open.c:1246
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 free_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page mm/page_alloc.c:3391 [inline]
 free_the_page mm/page_alloc.c:5443 [inline]
 __free_pages+0x146/0x3b0 mm/page_alloc.c:5454
 free_pages+0x82/0x90 mm/page_alloc.c:5465
 selinux_genfs_get_sid+0x20b/0x250 security/selinux/hooks.c:1332
 inode_doinit_with_dentry+0x879/0xd70 security/selinux/hooks.c:1529
 selinux_d_instantiate+0x27/0x40 security/selinux/hooks.c:6395
 security_d_instantiate+0x9e/0xf0 security/security.c:1980
 d_splice_alias+0x6d/0x390 fs/dcache.c:3038
 kernfs_iop_lookup+0x2c5/0x310 fs/kernfs/dir.c:1178
 lookup_open fs/namei.c:3234 [inline]
 open_last_lookups fs/namei.c:3325 [inline]
 path_openat+0x1140/0x31c0 fs/namei.c:3514
 do_filp_open+0x1e2/0x410 fs/namei.c:3544
 do_sys_openat2+0x19f/0x750 fs/open.c:1219
 do_sys_open fs/open.c:1235 [inline]
 __do_sys_openat fs/open.c:1251 [inline]
 __se_sys_openat fs/open.c:1246 [inline]
 __x64_sys_openat+0x136/0x160 fs/open.c:1246
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff888110170b80: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
 ffff888110170c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888110170c80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                           ^
 ffff888110170d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888110170d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (2435):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/24 20:15 android13-5.10-lts f5a34916f66d c69befb3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/02/12 22:16 android13-5.10-lts e8b14e1cefe8 504cb1bf .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2025/12/30 04:19 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2025/09/20 20:09 android13-5.10-lts 911f602c2237 67c37560 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2025/06/12 15:10 android13-5.10-lts d76d4cd0623a 98683f8f .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2025/04/05 17:32 android13-5.10-lts 094fc3778d6b c53ea9c9 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2025/01/04 22:55 android13-5.10-lts 49e8ba0a684f f3558dbf .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2025/01/04 22:39 android13-5.10-lts 49e8ba0a684f f3558dbf .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/25 07:13 android13-5.10-lts f5a34916f66d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/25 02:32 android13-5.10-lts f5a34916f66d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/24 19:43 android13-5.10-lts f5a34916f66d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/23 18:55 android13-5.10-lts f5a34916f66d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/23 12:56 android13-5.10-lts f5a34916f66d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/23 05:39 android13-5.10-lts f5a34916f66d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/22 21:29 android13-5.10-lts f5a34916f66d 5f091fcc .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/22 13:49 android13-5.10-lts f5a34916f66d 5f091fcc .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/22 13:48 android13-5.10-lts f5a34916f66d 5f091fcc .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/22 10:23 android13-5.10-lts f5a34916f66d 70ae9b03 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/22 04:23 android13-5.10-lts f5a34916f66d 70ae9b03 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/22 03:03 android13-5.10-lts f5a34916f66d 70ae9b03 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/22 01:34 android13-5.10-lts f5a34916f66d 70ae9b03 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/21 23:49 android13-5.10-lts f5a34916f66d e195359d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/19 16:10 android13-5.10-lts f5a34916f66d 223544dc .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/19 11:58 android13-5.10-lts f5a34916f66d 223544dc .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/19 04:21 android13-5.10-lts f5a34916f66d 9f74d399 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/19 02:51 android13-5.10-lts f5a34916f66d 9f74d399 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/19 01:31 android13-5.10-lts f5a34916f66d 9f74d399 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/18 22:31 android13-5.10-lts f5a34916f66d 9f74d399 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/18 06:03 android13-5.10-lts 1b32327554da de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/18 04:26 android13-5.10-lts 1b32327554da de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/17 23:08 android13-5.10-lts 1b32327554da de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/17 17:59 android13-5.10-lts 1b32327554da de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/17 14:30 android13-5.10-lts 1b32327554da de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/16 00:00 android13-5.10-lts 1b32327554da 81fb92f3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/15 21:30 android13-5.10-lts 1b32327554da 81fb92f3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/15 15:26 android13-5.10-lts 1b32327554da 9cd3beaa .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/15 10:48 android13-5.10-lts 1b32327554da 9cd3beaa .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/15 04:47 android13-5.10-lts 1b32327554da 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/14 18:57 android13-5.10-lts 1b32327554da 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/14 14:43 android13-5.10-lts 1b32327554da 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/14 10:53 android13-5.10-lts 1b32327554da 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/14 08:20 android13-5.10-lts 1b32327554da 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/14 06:42 android13-5.10-lts 1b32327554da 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/13 17:08 android13-5.10-lts 1b32327554da fec2a7ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/13 07:46 android13-5.10-lts 1b32327554da a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/13 04:08 android13-5.10-lts 1b32327554da a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/13 00:10 android13-5.10-lts 1b32327554da a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/12 02:43 android13-5.10-lts 1b32327554da d168f260 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/11 02:46 android13-5.10-lts 5feb5545d40a 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/10 19:57 android13-5.10-lts 5feb5545d40a 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/10 17:44 android13-5.10-lts 5feb5545d40a 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2026/05/10 16:32 android13-5.10-lts 5feb5545d40a 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
2025/01/04 22:20 android13-5.10-lts 49e8ba0a684f f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in tc_setup_flow_action
* Struck through repros no longer work on HEAD.