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

Status: upstream: reported on 2026/08/05 13:55
Reported-by: syzbot+802bf88adfebfa7c354f@syzkaller.appspotmail.com
First crash: 23d, last: 10h36m
▶ ▼ Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: vmalloc-out-of-bounds Write in imageblit fbdev 21 syz, C 104 1767d 2061d 20/29 fixed on 2021/11/10 00:50
upstream KASAN: vmalloc-out-of-bounds Write in imageblit (6) prio:high fbdev 21 syz, C 8246 18m 299d 0/29 upstream: reported C repro on 2025/11/02 21:10
linux-5.15 KASAN: vmalloc-out-of-bounds Write in imageblit 21 16 2d16h 22d 0/3 upstream: reported on 2026/08/06 13:30
linux-6.1 KASAN: vmalloc-out-of-bounds Write in imageblit 21 72 9h35m 22d 0/3 upstream: reported on 2026/08/07 05:50
upstream KASAN: vmalloc-out-of-bounds Write in imageblit (5) fbdev 21 syz, C 1075 303d 354d 29/29 fixed on 2025/10/29 21:02
upstream KASAN: vmalloc-out-of-bounds Write in imageblit (4) fbdev 21 syz, C 3869 358d 738d 29/29 fixed on 2025/09/04 16:57
upstream KASAN: vmalloc-out-of-bounds Write in imageblit (3) fbdev 21 2 1131d 1127d 0/29 auto-obsoleted due to no activity on 2023/10/23 10:50
upstream KASAN: vmalloc-out-of-bounds Write in imageblit (2) fbdev 21 syz, C done 701 1456d 1744d 22/29 fixed on 2023/02/24 13:50
upstream KASAN: vmalloc-out-of-bounds Write in sys_imageblit fbdev 21 syz, C 91 2086d 2453d 0/29 auto-obsoleted due to no activity on 2022/12/09 01:09
upstream BUG: unable to handle kernel paging request in sys_imageblit fbdev 8 syz 16 2083d 2453d 0/29 auto-obsoleted due to no activity on 2022/08/31 01:46

Sample crash report:
==================================================================
BUG: KASAN: vmalloc-out-of-bounds in fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline]
BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x1bac/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
Write of size 4 at addr ffffc90003ec9f80 by task syz.2.119/6471

CPU: 1 PID: 6471 Comm: syz.2.119 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline]
 sys_imageblit+0x1bac/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
 drm_fbdev_generic_defio_imageblit+0x2c/0x110 drivers/gpu/drm/drm_fbdev_generic.c:37
 cw_putcs_aligned drivers/video/fbdev/core/fbcon_cw.c:110 [inline]
 cw_putcs+0x15f3/0x18a0 drivers/video/fbdev/core/fbcon_cw.c:158
 fbcon_putcs+0x35c/0x520 drivers/video/fbdev/core/fbcon.c:1301
 do_update_region+0x4e9/0x640 drivers/tty/vt/vt.c:623
 invert_screen+0x8e2/0xa70 drivers/tty/vt/vt.c:748
 highlight drivers/tty/vt/selection.c:57 [inline]
 clear_selection+0x59/0x70 drivers/tty/vt/selection.c:85
 vc_do_resize+0x6f2/0x17f0 drivers/tty/vt/vt.c:1206
 fbcon_modechanged+0x80d/0x12b0 drivers/video/fbdev/core/fbcon.c:2715
 fbcon_rotate_all drivers/video/fbdev/core/fbcon.c:252 [inline]
 store_rotate_all+0x531/0x620 drivers/video/fbdev/core/fbcon.c:3260
 kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 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: 0033:0x7f6dbc39e159
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:00007f6dba5f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6dbc626180 RCX: 00007f6dbc39e159
RDX: 0000000000000002 RSI: 00002000000000c0 RDI: 0000000000000008
RBP: 00007f6dbc435024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6dbc626218 R14: 00007f6dbc626180 R15: 00007ffe83a5aa48
 </TASK>

The buggy address belongs to a 0-page vmalloc region starting at 0xffffc90003eca000 allocated at drm_gem_shmem_vmap+0x3c4/0x650 drivers/gpu/drm/drm_gem_shmem_helper.c:340
Memory state around the buggy address:
 ffffc90003ec9e80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90003ec9f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90003ec9f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc90003eca000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90003eca080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (18):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/29 00:33 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/27 12:19 linux-6.6.y dc6160265ffc 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/27 12:18 linux-6.6.y dc6160265ffc 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/27 12:18 linux-6.6.y dc6160265ffc 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/26 10:20 linux-6.6.y dc6160265ffc 6a91adb4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/25 04:39 linux-6.6.y dc6160265ffc 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/19 19:27 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/14 14:48 linux-6.6.y d27334b2888c 6f9b3e89 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/12 19:40 linux-6.6.y d27334b2888c 359b2492 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/12 03:42 linux-6.6.y d27334b2888c f8d35649 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/12 03:42 linux-6.6.y d27334b2888c f8d35649 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/10 09:53 linux-6.6.y d27334b2888c 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/10 05:45 linux-6.6.y d27334b2888c 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/07 22:13 linux-6.6.y 6436c12a2ced e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/07 05:33 linux-6.6.y 80dfb0405055 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/05 13:55 linux-6.6.y aa0e49877a2e 52aa2820 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/19 05:18 linux-6.6.y d27334b2888c 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in imageblit
2026/08/19 05:07 linux-6.6.y d27334b2888c 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in imageblit
* Struck through repros no longer work on HEAD.