WARNING in bitmap_parse_user

Status: upstream: reported C repro on 2026/07/31 03:39
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+304ce94b7efa3a6313d4@syzkaller.appspotmail.com
First crash: 9d19h, last: 18h03m
Bug presence (2)
Date Name Commit Repro Result
2026/08/09 linux-6.6.y (ToT) 6436c12a2ced C [report] WARNING in bitmap_parse_user
2026/08/09 upstream (ToT) 06cf61899d64 C Didn't crash
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING in bitmap_parse_user -1 syz, C 3 3d09h 3d10h 0/3 upstream: reported C repro on 2026/08/06 12:00
linux-6.1 WARNING in bitmap_parse_user -1 syz, C 5 3d17h 9d18h 0/3 upstream: reported C repro on 2026/07/31 03:46
android-6-12 WARNING in bitmap_parse_user -1 syz, C 11 9h36m 10d 0/1 premoderation: reported C repro on 2026/07/30 09:20
upstream WARNING in bitmap_parse_user trace -1 syz, C 83 581d 601d 28/29 fixed on 2025/05/06 15:33

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5932 at mm/page_alloc.c:4477 __alloc_pages+0x2e4/0x460 mm/page_alloc.c:4477
Modules linked in:
CPU: 1 PID: 5932 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__alloc_pages+0x2e4/0x460 mm/page_alloc.c:4477
Code: 0c 25 28 00 00 00 48 3b 8c 24 a0 00 00 00 0f 85 9f 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 c6 05 92 1b a3 0c 01 <0f> 0b eb a4 a9 00 00 08 00 8b 74 24 0c 75 3e 44 89 f1 81 e1 7f ff
RSP: 0018:ffffc90003377a20 EFLAGS: 00010246
RAX: ffffc90003377a00 RBX: 1ffff9200066ef48 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc90003377a88
RBP: ffffc90003377b10 R08: ffffc90003377a87 R09: 0000000000000000
R10: ffffc90003377a60 R11: fffff5200066ef51 R12: 0000000000000013
R13: 0000000000000000 R14: 0000000000040cc0 R15: dffffc0000000000
FS:  0000555594ccd500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ce63fff CR3: 0000000074291000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 __alloc_pages_node include/linux/gfp.h:237 [inline]
 alloc_pages_node include/linux/gfp.h:260 [inline]
 __kmalloc_large_node+0x8c/0x1f0 mm/slab_common.c:1148
 __do_kmalloc_node mm/slab_common.c:995 [inline]
 __kmalloc_node_track_caller+0x110/0x230 mm/slab_common.c:1027
 memdup_user_nul+0x2c/0xf0 mm/util.c:284
 bitmap_parse_user+0x23/0x70 lib/bitmap.c:464
 cpumask_parse_user include/linux/cpumask.h:777 [inline]
 write_irq_affinity kernel/irq/proc.c:153 [inline]
 irq_affinity_proc_write+0x13c/0x230 kernel/irq/proc.c:182
 pde_write fs/proc/inode.c:340 [inline]
 proc_reg_write+0x1e4/0x2d0 fs/proc/inode.c:352
 vfs_write+0x299/0x9a0 fs/read_write.c:582
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f691119e019
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:00007ffdd517c918 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6911425fa0 RCX: 00007f691119e019
RDX: 00000000fffffdd4 RSI: 0000200000000340 RDI: 0000000000000003
RBP: 00007f691123500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6911425fac R14: 00007f6911425fa0 R15: 00007f6911425fa0
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/02 14:45 linux-6.6.y a1153c0deb44 e611ffe1 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in bitmap_parse_user
2026/08/06 04:29 linux-6.6.y aa0e49877a2e cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in bitmap_parse_user
2026/08/06 04:29 linux-6.6.y aa0e49877a2e cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in bitmap_parse_user
2026/07/31 03:39 linux-6.6.y a1153c0deb44 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in bitmap_parse_user
2026/07/31 03:38 linux-6.6.y a1153c0deb44 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in bitmap_parse_user
* Struck through repros no longer work on HEAD.