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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: 384d, last: 24m
▶ ▼ Discussions (12)
Title Replies (including bot) Last reply
[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

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 ffffc90004929000 by task syz.0.585/8692

CPU: 0 UID: 0 PID: 8692 Comm: syz.0.585 Tainted: G     U       L      syzkaller #0 PREEMPT(full) 
Tainted: [U]=USER, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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/0x1d0 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+0x314/0x650 drivers/video/fbdev/core/fbcon.c:2014
 con_scroll+0x464/0x690 drivers/tty/vt/vt.c:616
 csi_L drivers/tty/vt/vt.c:2174 [inline]
 csi_ECMA.constprop.0+0xc57/0x3b60 drivers/tty/vt/vt.c:2611
 do_con_trol drivers/tty/vt/vt.c:2829 [inline]
 do_con_write+0x3946/0x4a10 drivers/tty/vt/vt.c:3324
 con_write+0x23/0xb0 drivers/tty/vt/vt.c:3660
 process_output_block drivers/tty/n_tty.c:557 [inline]
 n_tty_write+0x431/0x11c0 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+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff12659cdd9
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:00007ff1273b4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ff126815fa0 RCX: 00007ff12659cdd9
RDX: 000000000000fdef RSI: 0000200000000000 RDI: 0000000000000005
RBP: 00007ff126632d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff126816038 R14: 00007ff126815fa0 R15: 00007ffc9c0241a8
 </TASK>

The buggy address belongs to a 0-page vmalloc region starting at 0xffffc90004629000 allocated at drm_gem_shmem_vmap_locked+0x553/0x860 drivers/gpu/drm/drm_gem_shmem_helper.c:395
Memory state around the buggy address:
 ffffc90004928f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90004928f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90004929000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc90004929080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90004929100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

Crashes (241):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/05 10:06 upstream a293ec25d59d 114c483e .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/05/04 14:38 upstream 6d35786de281 85f1bcf2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/05/04 07:09 upstream 6d35786de281 a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/05/03 17:49 upstream f377d0025eb0 a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/05/01 01:55 upstream e75a43c7cec4 a7464baf .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/30 07:35 upstream 57b8e2d666a3 005438fc .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/29 21:40 upstream 57b8e2d666a3 005438fc .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/21 13:25 upstream b4e07588e743 3f2e655b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/19 02:32 upstream eb5249b12507 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/14 17:29 upstream d60bc1401583 362d1323 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/13 10:11 upstream 028ef9c96e96 9530ccf9 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/13 06:48 upstream 028ef9c96e96 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/12 21:17 upstream f5459048c38a 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/12 16:30 upstream f5459048c38a 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/12 06:45 upstream e753c16cb3dd 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/10 14:20 upstream 9a9c8ce300cd 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/10 10:31 upstream 9a9c8ce300cd 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/09 23:20 upstream a55f7f5f29b3 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/09 12:46 upstream 7f87a5ea75f0 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/09 04:12 upstream 7f87a5ea75f0 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/06 07:38 upstream 591cd656a1bf 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/05 02:55 upstream 3aae9383f42f 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/04 13:45 upstream 7ca6d1cfec80 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/04 04:42 upstream 631919fb12fe 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/03 11:04 upstream d8a9a4b11a13 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/02 07:41 upstream 9147566d8016 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/02 05:38 upstream 9147566d8016 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/31 18:13 upstream d0c3bcd5b897 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/31 18:13 upstream d0c3bcd5b897 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/28 13:55 upstream 7df48e363130 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/25 11:21 upstream 24f9515de877 b4723e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/22 09:18 upstream 113ae7b4decc 5b92003d .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/19 16:28 upstream 8a30aeb0d1b4 bd6dcb30 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/16 01:49 upstream f338e7738378 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/14 14:07 upstream 1c9982b49613 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/12 10:06 upstream 80234b5ab240 4efadf07 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/12 00:40 upstream b29fb8829bff 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/11 14:02 upstream b29fb8829bff 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: vmalloc-out-of-bounds Write in fillrect
2026/03/11 01:36 upstream b4f0dd314b39 86914af9 .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
2026/03/10 07:31 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
2026/03/10 01:29 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
2026/04/10 22:22 upstream 7c6c4ed80b87 38c8e246 .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
2026/04/01 08:32 upstream 9147566d8016 9a1f7828 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: vmalloc-out-of-bounds Write in fillrect
2026/04/22 21:48 upstream 2a4c0c11c019 0e869ba2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto BUG: unable to handle kernel paging request in fillrect
2026/04/12 18:21 upstream f5459048c38a 38c8e246 .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.