Hello, syzbot found the following issue on: HEAD commit: fa55b7dcdc43 Linux 5.16-rc1 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15fe2569b00000 kernel config: https://syzkaller.appspot.com/x/.config?x=6d3b8fd1977c1e73 dashboard link: https://syzkaller.appspot.com/bug?extid=14b0e8f3fd1612e35350 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+14b0e8f3fd1612e35350@xxxxxxxxxxxxxxxxxxxxxxxxx 524155 pages RAM 0 pages HighMem/MovableOnly 163742 pages reserved 0 pages cma reserved ================================================================== BUG: KASAN: vmalloc-out-of-bounds in fast_imageblit drivers/video/fbdev/core/sysimgblt.c:229 [inline] BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x12f4/0x1430 drivers/video/fbdev/core/sysimgblt.c:275 Write of size 4 at addr ffffc90004631000 by task syz-executor.0/7913 CPU: 0 PID: 7913 Comm: syz-executor.0 Not tainted 5.16.0-rc1-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0xf/0x320 mm/kasan/report.c:247 __kasan_report mm/kasan/report.c:433 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:450 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:229 [inline] sys_imageblit+0x12f4/0x1430 drivers/video/fbdev/core/sysimgblt.c:275 drm_fb_helper_sys_imageblit drivers/gpu/drm/drm_fb_helper.c:794 [inline] drm_fbdev_fb_imageblit+0x15c/0x350 drivers/gpu/drm/drm_fb_helper.c:2282 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:124 [inline] bit_putcs+0x6e1/0xd20 drivers/video/fbdev/core/bitblit.c:173 fbcon_putcs+0x353/0x440 drivers/video/fbdev/core/fbcon.c:1277 do_update_region+0x399/0x630 drivers/tty/vt/vt.c:676 redraw_screen+0x61f/0x740 drivers/tty/vt/vt.c:1035 fbcon_modechanged+0x58c/0x6c0 drivers/video/fbdev/core/fbcon.c:2182 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:2227 do_fb_ioctl+0x62e/0x690 drivers/video/fbdev/core/fbmem.c:1114 fb_compat_ioctl+0x17e/0x610 drivers/video/fbdev/core/fbmem.c:1313 __do_compat_sys_ioctl+0x1c7/0x290 fs/ioctl.c:972 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c RIP: 0023:0xf6e67549 Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f44615fc EFLAGS: 00000296 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000004601 RDX: 0000000020000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> Memory state around the buggy address: ffffc90004630f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffffc90004630f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffffc90004631000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffffc90004631080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90004631100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ================================================================== ---------------- Code disassembly (best guess): 0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi 4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d a: 10 06 adc %al,(%rsi) c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 10: 10 07 adc %al,(%rdi) 12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi 16: 10 08 adc %cl,(%rax) 18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1c: 00 00 add %al,(%rax) 1e: 00 00 add %al,(%rax) 20: 00 51 52 add %dl,0x52(%rcx) 23: 55 push %rbp 24: 89 e5 mov %esp,%ebp 26: 0f 34 sysenter 28: cd 80 int $0x80 * 2a: 5d pop %rbp <-- trapping instruction 2b: 5a pop %rdx 2c: 59 pop %rcx 2d: c3 retq 2e: 90 nop 2f: 90 nop 30: 90 nop 31: 90 nop 32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
