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

Status: upstream: reported on 2026/08/06 13:30
Reported-by: syzbot+23839731b8735c36866b@syzkaller.appspotmail.com
First crash: 11d, last: 1d15h
▶ ▼ 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 1756d 2049d 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 7585 9m 287d 0/29 upstream: reported C repro on 2025/11/02 21:10
linux-6.1 KASAN: vmalloc-out-of-bounds Write in imageblit 21 32 3h40m 10d 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 292d 343d 29/29 fixed on 2025/10/29 21:02
upstream KASAN: vmalloc-out-of-bounds Write in imageblit (4) fbdev 21 syz, C 3869 347d 726d 29/29 fixed on 2025/09/04 16:57
upstream KASAN: vmalloc-out-of-bounds Write in imageblit (3) fbdev 21 2 1119d 1115d 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 1444d 1732d 22/29 fixed on 2023/02/24 13:50
linux-6.6 KASAN: vmalloc-out-of-bounds Write in imageblit 21 9 3d05h 12d 0/2 upstream: reported on 2026/08/05 13:55
upstream KASAN: vmalloc-out-of-bounds Write in sys_imageblit fbdev 21 syz, C 91 2074d 2442d 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 2072d 2442d 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+0x1ba8/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
Write of size 4 at addr ffffc900044318a0 by task syz.2.785/7427

CPU: 0 PID: 7427 Comm: syz.2.785 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline]
 sys_imageblit+0x1ba8/0x25d0 drivers/video/fbdev/core/sysimgblt.c:323
 drm_fb_helper_sys_imageblit+0x2e/0x510 drivers/gpu/drm/drm_fb_helper.c:793
 soft_cursor+0x9fd/0xc30 drivers/video/fbdev/core/softcursor.c:74
 bit_cursor+0x1699/0x1f00 drivers/video/fbdev/core/bitblit.c:404
 set_cursor drivers/tty/vt/vt.c:920 [inline]
 con_flush_chars+0x1f6/0x270 drivers/tty/vt/vt.c:3368
 con_write+0x29/0x40 drivers/tty/vt/vt.c:3296
 process_output_block drivers/tty/n_tty.c:592 [inline]
 n_tty_write+0xd19/0x1220 drivers/tty/n_tty.c:2339
 do_tty_write drivers/tty/tty_io.c:1038 [inline]
 file_tty_write+0x50c/0x8a0 drivers/tty/tty_io.c:1110
 call_write_iter include/linux/fs.h:2173 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7ff217e880d9
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:00007ff2160e0028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ff21810ffa0 RCX: 00007ff217e880d9
RDX: 0000000000001006 RSI: 0000200000001a00 RDI: 0000000000000005
RBP: 00007ff217f1f024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff218110038 R14: 00007ff21810ffa0 R15: 00007ffc88a246a8
 </TASK>


Memory state around the buggy address:
 ffffc90004431780: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90004431800: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90004431880: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                               ^
 ffffc90004431900: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90004431980: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/15 02:31 linux-5.15.y aabd761612db 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/14 21:42 linux-5.15.y aabd761612db 6f9b3e89 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/14 16:09 linux-5.15.y aabd761612db 6f9b3e89 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/13 19:33 linux-5.15.y aabd761612db b13552fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/13 19:33 linux-5.15.y aabd761612db b13552fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/07 03:22 linux-5.15.y 9c7634c60784 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/07 03:22 linux-5.15.y 9c7634c60784 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/06 13:29 linux-5.15.y 6e2fd6534337 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: vmalloc-out-of-bounds Write in imageblit
2026/08/16 05:21 linux-5.15.y aabd761612db 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan BUG: unable to handle kernel paging request in imageblit
2026/08/15 23:03 linux-5.15.y aabd761612db 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan BUG: unable to handle kernel paging request in imageblit
2026/08/08 08:34 linux-5.15.y aabd761612db 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan BUG: unable to handle kernel paging request in imageblit
* Struck through repros no longer work on HEAD.