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

Status: upstream: reported on 2025/05/28 09:22
Subsystems: fbdev
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+7a63ce155648954e749b@syzkaller.appspotmail.com
First crash: 501d, last: 8m
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
ce4f0ca9 repro-c Reproduced: ✅ ❓ KASAN: vmalloc-out-of-bounds Write in fillrect 2026/08/07 14:02 2026/08/07 23:41 2026/08/08 01:45 e4ef95d6
57bd59be assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: vmalloc-out-of-bounds Write in fillrect 2026/05/24 07:12 2026/05/24 07:12 2026/05/24 08:16 c69befb3
▶ ▼ Discussions (16)
Title Replies (including bot) Last reply
[syzbot] Monthly fbdev report (Aug 2026) 0 (1) 2026/08/22 04:32
[syzbot] Monthly fbdev report (Jul 2026) 0 (1) 2026/07/21 20:32
[syzbot] Monthly fbdev report (Jun 2026) 0 (1) 2026/06/20 12:32
[syzbot] Monthly fbdev report (May 2026) 0 (1) 2026/05/20 12:32
[syzbot] Monthly fbdev report (Apr 2026) 0 (1) 2026/04/20 07:05
[syzbot] Monthly fbdev report (Mar 2026) 0 (1) 2026/03/19 10:23
[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
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/08/08 08:25 19m nogikh@google.com upstream report log

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 ffffc90004ad1000 by task syz.0.345/8379

CPU: 0 UID: 0 PID: 8379 Comm: syz.0.345 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
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+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 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:72
 __fbcon_clear+0x633/0x760 drivers/video/fbdev/core/fbcon.c:1375
 fbcon_scroll+0x48b/0x650 drivers/video/fbdev/core/fbcon.c:1927
 con_scroll+0x464/0x690 drivers/tty/vt/vt.c:616
 csi_M drivers/tty/vt/vt.c:2191 [inline]
 csi_ECMA.constprop.0+0x1238/0x3b60 drivers/tty/vt/vt.c:2614
 do_con_trol drivers/tty/vt/vt.c:2829 [inline]
 do_con_write+0x3660/0x4a30 drivers/tty/vt/vt.c:3325
 con_write+0x23/0xb0 drivers/tty/vt/vt.c:3661
 process_output_block drivers/tty/n_tty.c:557 [inline]
 n_tty_write+0x431/0x1160 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/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f50b399de99
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:00007f50b486b028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f50b3c25fa0 RCX: 00007f50b399de99
RDX: 000000000000fdef RSI: 0000200000000000 RDI: 0000000000000001
RBP: 00007f50b3a33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f50b3c26038 R14: 00007f50b3c25fa0 R15: 00007fff02aecbc8
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
Memory state around the buggy address:
 ffffc90004ad0f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90004ad0f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90004ad1000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc90004ad1080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90004ad1100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

Crashes (561):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/26 03:06 upstream 3dab139d4795 4a865b71 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/07/25 23:25 upstream 3dab139d4795 4a865b71 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/05/19 09:32 upstream ab5fce87a778 2aa09d96 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/10 11:39 upstream 1f318b96cc84 6972f302 .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
2026/08/29 08:31 upstream cf72cbb39da8 2f52988a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/28 21:06 upstream 818bebeb63dd 41d151d4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/28 15:51 upstream 818bebeb63dd 41d151d4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/28 13:17 upstream 818bebeb63dd 41d151d4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/27 17:26 upstream 818bebeb63dd c53a1b9c .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/27 15:58 upstream 818bebeb63dd c53a1b9c .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/26 19:33 upstream 818bebeb63dd a2b77b9e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/26 07:58 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/26 06:35 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/26 04:49 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/25 19:08 upstream 818bebeb63dd a9a1fc32 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/25 14:30 upstream 818bebeb63dd a9a1fc32 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/25 08:47 upstream 818bebeb63dd 614e416a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/25 06:36 upstream 818bebeb63dd 614e416a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/25 03:51 upstream 818bebeb63dd 614e416a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/24 23:12 upstream 818bebeb63dd 614e416a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/24 10:37 upstream 818bebeb63dd b55bd4c3 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/24 05:07 upstream 818bebeb63dd 1e72964b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/23 22:50 upstream 818bebeb63dd 1e72964b .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
2026/08/30 13:43 upstream 08dbfad3f504 2f52988a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/30 09:59 upstream 08dbfad3f504 2f52988a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/10 06:33 linux-next cc2b5f627e8c 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/30 15:33 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/30 04:08 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/30 00:08 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/29 14:08 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/29 12:02 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/28 19:59 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 bcbc8ceb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/28 17:56 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 bcbc8ceb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/28 11:33 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/28 05:04 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/28 03:41 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/27 13:17 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 68f892e99df9 a2b77b9e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/27 02:36 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 68f892e99df9 a2b77b9e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/26 11:11 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 68f892e99df9 6a91adb4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/26 02:33 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 68f892e99df9 6a91adb4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/25 21:57 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 68f892e99df9 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/25 18:16 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 68f892e99df9 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/25 12:44 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 68f892e99df9 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/24 12:09 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 21d6ac051080 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/08/28 06:42 upstream 818bebeb63dd e2fa417d .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream BUG: unable to handle kernel paging request in fillrect
2026/08/27 06:43 upstream 818bebeb63dd a2b77b9e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream BUG: unable to handle kernel paging request in fillrect
2026/08/26 00:34 upstream 818bebeb63dd 6a91adb4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream BUG: unable to handle kernel paging request in fillrect
2026/08/25 00:40 upstream 818bebeb63dd 614e416a .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream BUG: unable to handle kernel paging request in fillrect
2026/08/24 17:11 upstream 818bebeb63dd b55bd4c3 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream BUG: unable to handle kernel paging request in fillrect
2026/08/22 18:30 upstream 818bebeb63dd 1e72964b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: stack-out-of-bounds Write in fillrect
2026/08/29 04:33 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 bcbc8ceb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: unable to handle kernel paging request in fillrect
* Struck through repros no longer work on HEAD.