syzbot


KASAN: use-after-free Read in ieee80211_monitor_select_queue

Status: upstream: reported on 2026/01/29 16:08
Reported-by: syzbot+878643e0580bc580f883@syzkaller.appspotmail.com
First crash: 10d, last: 5d09h

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in ieee80211_monitor_select_queue+0x23a/0x240 net/mac80211/iface.c:764
Read of size 2 at addr ffff8880487fedfb by task syz.6.1079/10327

CPU: 1 PID: 10327 Comm: syz.6.1079 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 ieee80211_monitor_select_queue+0x23a/0x240 net/mac80211/iface.c:764
 netdev_core_pick_tx+0x118/0x2e0 net/core/dev.c:4171
 __dev_queue_xmit+0x756/0x2fd0 net/core/dev.c:4248
 packet_snd net/packet/af_packet.c:3089 [inline]
 packet_sendmsg+0x3dba/0x5060 net/packet/af_packet.c:3120
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
 __sys_sendmsg net/socket.c:2528 [inline]
 __do_sys_sendmsg net/socket.c:2537 [inline]
 __se_sys_sendmsg+0x1af/0x290 net/socket.c:2535
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f9897cc7eb9
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:00007f9895f23028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9897f42fa0 RCX: 00007f9897cc7eb9
RDX: 0000000000004005 RSI: 0000200000000280 RDI: 0000000000000005
RBP: 00007f9897d35c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9897f43038 R14: 00007f9897f42fa0 R15: 00007fffd9d76b58
 </TASK>

The buggy address belongs to the page:
page:ffffea000121ff80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x487fe
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea000121ff48 ffffea000121ffc8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 10309, ts 379608122561, free_ts 379733526618
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5487
 vm_area_alloc_pages mm/vmalloc.c:2876 [inline]
 __vmalloc_area_node mm/vmalloc.c:2932 [inline]
 __vmalloc_node_range+0x4b2/0x8b0 mm/vmalloc.c:3037
 vmalloc_user+0x70/0x80 mm/vmalloc.c:3173
 kcov_mmap+0x27/0x120 kernel/kcov.c:474
 call_mmap include/linux/fs.h:2178 [inline]
 mmap_file+0x5d/0xb0 mm/util.c:1092
 __mmap_region mm/mmap.c:1796 [inline]
 mmap_region+0xf88/0x1650 mm/mmap.c:2933
 do_mmap+0x819/0xe90 mm/mmap.c:1586
 vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:551
 ksys_mmap_pgoff+0x54b/0x790 mm/mmap.c:1635
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 __vunmap+0x8b9/0xa50 mm/vmalloc.c:2628
 kcov_mmap+0x89/0x120 kernel/kcov.c:498
 call_mmap include/linux/fs.h:2178 [inline]
 mmap_file+0x5d/0xb0 mm/util.c:1092
 __mmap_region mm/mmap.c:1796 [inline]
 mmap_region+0xf88/0x1650 mm/mmap.c:2933
 do_mmap+0x819/0xe90 mm/mmap.c:1586
 vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:551
 ksys_mmap_pgoff+0x54b/0x790 mm/mmap.c:1635
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff8880487fec80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880487fed00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880487fed80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8880487fee00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880487fee80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/04 02:52 linux-5.15.y 9eec9a14ee10 42b01fab .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in ieee80211_monitor_select_queue
2026/02/03 02:28 linux-5.15.y 9eec9a14ee10 d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in ieee80211_monitor_select_queue
2026/01/29 16:08 linux-5.15.y 9eec9a14ee10 aeb6fdd5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in ieee80211_monitor_select_queue
2026/02/03 02:27 linux-5.15.y 9eec9a14ee10 d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in ieee80211_monitor_select_queue
2026/02/03 01:36 linux-5.15.y 9eec9a14ee10 d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in ieee80211_monitor_select_queue
2026/02/02 13:32 linux-5.15.y 9eec9a14ee10 018ebef2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in ieee80211_monitor_select_queue
* Struck through repros no longer work on HEAD.