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KASAN: vmalloc-out-of-bounds Write in fillrect

Status: upstream: reported on 2025/05/28 09:22
Subsystems: fbdev
[Documentation on labels]
Reported-by: syzbot+7a63ce155648954e749b@syzkaller.appspotmail.com
First crash: 319d, last: 1d23h
▶ ▼ Discussions (10)
Title Replies (including bot) Last reply
[syzbot] Monthly fbdev report (Feb 2026) 0 (1) 2026/02/16 07:33
[PATCH] fbdev: sys_fillrect: Add bounds checking to prevent vmalloc-out-of-bounds 3 (3) 2026/01/24 16:53
[syzbot] Monthly fbdev report (Jan 2026) 0 (1) 2026/01/15 13:09
[syzbot] Monthly fbdev report (Dec 2025) 0 (1) 2025/12/16 01:32
[syzbot] Monthly fbdev report (Nov 2025) 0 (1) 2025/11/14 18:41
[syzbot] Monthly fbdev report (Sep 2025) 0 (1) 2025/09/12 21:33
[syzbot] Monthly fbdev report (Aug 2025) 0 (1) 2025/08/12 12:44
[syzbot] Monthly fbdev report (Jul 2025) 0 (1) 2025/07/14 07:22
[syzbot] Monthly fbdev report (Jun 2025) 0 (1) 2025/06/11 07:46
[syzbot] [fbdev?] KASAN: vmalloc-out-of-bounds Write in fillrect 0 (1) 2025/05/28 09:22

Sample crash report:
==================================================================
BUG: KASAN: vmalloc-out-of-bounds in fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline]
BUG: KASAN: vmalloc-out-of-bounds in bitfill drivers/video/fbdev/core/fb_fillrect.h:133 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_fillrect_static drivers/video/fbdev/core/fb_fillrect.h:219 [inline]
BUG: KASAN: vmalloc-out-of-bounds in fb_fillrect drivers/video/fbdev/core/fb_fillrect.h:278 [inline]
BUG: KASAN: vmalloc-out-of-bounds in sys_fillrect+0x174a/0x1910 drivers/video/fbdev/core/sysfillrect.c:24
Write of size 8 at addr ffffc900042a9000 by task syz.0.1994/13858

CPU: 1 UID: 0 PID: 13858 Comm: syz.0.1994 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x156/0x4c9 mm/kasan/report.c:482
 kasan_report+0xdf/0x1e0 mm/kasan/report.c:595
 fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline]
 bitfill drivers/video/fbdev/core/fb_fillrect.h:133 [inline]
 fb_fillrect_static drivers/video/fbdev/core/fb_fillrect.h:219 [inline]
 fb_fillrect drivers/video/fbdev/core/fb_fillrect.h:278 [inline]
 sys_fillrect+0x174a/0x1910 drivers/video/fbdev/core/sysfillrect.c:24
 drm_fbdev_shmem_defio_fillrect+0x22/0x140 drivers/gpu/drm/drm_fbdev_shmem.c:39
 bit_clear+0x17d/0x220 drivers/video/fbdev/core/bitblit.c:73
 __fbcon_clear+0x633/0x760 drivers/video/fbdev/core/fbcon.c:1327
 fbcon_scroll+0x48b/0x650 drivers/video/fbdev/core/fbcon.c:1881
 con_scroll+0x464/0x690 drivers/tty/vt/vt.c:582
 csi_M drivers/tty/vt/vt.c:2134 [inline]
 csi_ECMA drivers/tty/vt/vt.c:2553 [inline]
 do_con_trol drivers/tty/vt/vt.c:2727 [inline]
 do_con_write+0x6883/0x8540 drivers/tty/vt/vt.c:3222
 con_write+0x23/0xb0 drivers/tty/vt/vt.c:3558
 process_output_block drivers/tty/n_tty.c:557 [inline]
 n_tty_write+0x44f/0x12d0 drivers/tty/n_tty.c:2366
 iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
 file_tty_write.isra.0+0x4d2/0x890 drivers/tty/tty_io.c:1081
 tty_write drivers/tty/tty_io.c:1102 [inline]
 redirected_tty_write drivers/tty/tty_io.c:1125 [inline]
 redirected_tty_write+0xd4/0x120 drivers/tty/tty_io.c:1105
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1070 fs/read_write.c:688
 ksys_write+0x12a/0x250 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feda599c799
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:00007feda693b028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007feda5c15fa0 RCX: 00007feda599c799
RDX: 000000000000fdef RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007feda5a32bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007feda5c16038 R14: 00007feda5c15fa0 R15: 00007ffd7cadcb18
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
Memory state around the buggy address:
 ffffc900042a8f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc900042a8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc900042a9000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc900042a9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc900042a9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

Crashes (172):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/27 10:41 upstream 3f4a08e64442 a2f13f71 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/23 21:15 upstream 6de23f81a5e0 7c9658af .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/21 11:12 upstream a95f71ad3e2e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/20 18:17 upstream 8bf22c33e7a1 741f5161 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/20 12:25 upstream 8bf22c33e7a1 17d780d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/19 10:32 upstream 956b9cbd7f15 746545b8 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/15 08:46 upstream ca4ee40bf13d 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/15 02:57 upstream 3e48a11675c5 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/14 04:26 upstream cee73b1e840c 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/13 10:06 upstream 7449f86bafcd 6a673c50 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/12 15:38 upstream 37a93dd5c49b 504cb1bf .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/12 12:49 upstream 37a93dd5c49b 76a109e2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/09 16:25 upstream 05f7e89ab973 df949cd9 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/08 05:22 upstream e7aa57247700 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/05 14:30 upstream f14faaf3a1fb 4936e85c .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/03 02:23 upstream dee65f79364c d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/31 09:00 upstream 283073725700 c75a2f6e .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/29 21:58 upstream 8dfce8991b95 aeb6fdd5 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/21 12:22 upstream 6c790212c588 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/18 04:59 upstream d12453c7e281 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/14 16:41 upstream c537e12daeec d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/14 13:39 upstream c537e12daeec d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/06 18:41 upstream f0b9d8eb98df d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/05 17:21 upstream 3609fa95fb0f d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/03 09:01 upstream 805f9a061372 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/01/02 04:03 upstream b69053dd3ffb d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2025/12/12 07:45 upstream d358e5254674 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2025/12/12 00:45 upstream d358e5254674 d1b870e1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/22 02:40 upstream 2eba5e05d9bc 4fb8ef37 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/21 05:28 upstream 8e621c9a3375 280ea308 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2025/05/20 18:50 upstream a5806cd506af b47f9e02 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2025/12/05 01:55 upstream 6dfafbd0299a d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/12/04 15:51 upstream cc25df3e2e22 d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/12/04 01:34 upstream 3f9f0252130e d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/30 12:00 upstream 6bda50f4333f d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/29 20:12 upstream 19eef1d98eed d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/29 16:59 upstream 19eef1d98eed d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/27 23:09 upstream 765e56e41a5a e8331348 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/27 05:40 upstream 4941a17751c9 e8331348 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/24 06:36 upstream d0e88704d96c 4fb8ef37 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/19 21:11 upstream 23cb64fb7625 26ee5237 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/12 21:59 upstream 24172e0d7990 07e030de .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/11/10 01:18 upstream 439fc29dfd3b 4e1406b4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2025/04/16 00:23 upstream 1a1d569a75f3 a95239b1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/16 14:07 upstream 0f2acd3148e0 84656fa6 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/11 10:43 upstream 192c0159402e 75707236 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/01 13:22 upstream 162b42445b58 6b8752f2 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/02/18 12:10 upstream 2961f841b025 39751c21 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto BUG: unable to handle kernel paging request in fillrect
2026/02/18 00:19 upstream d295082ea672 4db8fa92 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: stack-out-of-bounds Write in fillrect
* Struck through repros no longer work on HEAD.