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

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 63de3747 Merge tag 'tag-chrome-platform-for-v5.5' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1040fc41e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d189d07c6717979
dashboard link: https://syzkaller.appspot.com/bug?extid=e5fd3e65515b48c02a30
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e5fd3e...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in bitfill_aligned
drivers/video/fbdev/core/sysfillrect.c:54 [inline]
BUG: KASAN: vmalloc-out-of-bounds in bitfill_aligned+0x356/0x410
drivers/video/fbdev/core/sysfillrect.c:25
Write of size 8 at addr ffffc90008b11000 by task syz-executor.2/9476

CPU: 2 PID: 9476 Comm: syz-executor.2 Not tainted 5.4.0-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
print_address_description.constprop.0.cold+0x5/0x30b mm/kasan/report.c:374
__kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
kasan_report+0x12/0x20 mm/kasan/common.c:638
__asan_report_store8_noabort+0x17/0x20 mm/kasan/generic_report.c:140
bitfill_aligned drivers/video/fbdev/core/sysfillrect.c:54 [inline]
bitfill_aligned+0x356/0x410 drivers/video/fbdev/core/sysfillrect.c:25
sys_fillrect+0x421/0x7c0 drivers/video/fbdev/core/sysfillrect.c:291
drm_fb_helper_sys_fillrect+0x21/0x190 drivers/gpu/drm/drm_fb_helper.c:736
bit_clear_margins+0x30b/0x530 drivers/video/fbdev/core/bitblit.c:232
fbcon_clear_margins+0x1e9/0x250 drivers/video/fbdev/core/fbcon.c:1372
fbcon_switch+0xd7f/0x17f0 drivers/video/fbdev/core/fbcon.c:2354
redraw_screen+0x2b6/0x7d0 drivers/tty/vt/vt.c:997
fbcon_modechanged+0x5c3/0x790 drivers/video/fbdev/core/fbcon.c:2991
fbcon_update_vcs+0x42/0x50 drivers/video/fbdev/core/fbcon.c:3038
fb_set_var+0xb32/0xdd0 drivers/video/fbdev/core/fbmem.c:1051
do_fb_ioctl+0x390/0x7d0 drivers/video/fbdev/core/fbmem.c:1104
fb_ioctl+0xe6/0x130 drivers/video/fbdev/core/fbmem.c:1180
vfs_ioctl fs/ioctl.c:47 [inline]
file_ioctl fs/ioctl.c:545 [inline]
do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
__do_sys_ioctl fs/ioctl.c:756 [inline]
__se_sys_ioctl fs/ioctl.c:754 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a759
Code: bd b1 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 8b b1 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f8280324c88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000072bf00 RCX: 000000000045a759
RDX: 0000000020000040 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82803256d4
R13: 00000000004a9e78 R14: 00000000006ec2d8 R15: 00000000ffffffff


Memory state around the buggy address:
ffffc90008b10f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc90008b10f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffffc90008b11000: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
^
ffffc90008b11080: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
ffffc90008b11100: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
==================================================================


---
This bug 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 syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: fb33c651 Linux 5.6-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17dacd55e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9f894bd92023de02

dashboard link: https://syzkaller.appspot.com/bug?extid=e5fd3e65515b48c02a30
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11b8ca75e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=114800e5e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e5fd3e...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in bitfill_aligned drivers/video/fbdev/core/sysfillrect.c:54 [inline]

BUG: KASAN: vmalloc-out-of-bounds in bitfill_aligned+0x34b/0x410 drivers/video/fbdev/core/sysfillrect.c:25
Write of size 8 at addr ffffc90009621000 by task syz-executor767/9337

CPU: 3 PID: 9337 Comm: syz-executor767 Not tainted 5.6.0-rc6-syzkaller #0

Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]

dump_stack+0x188/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0x5/0x315 mm/kasan/report.c:374
__kasan_report.cold+0x1a/0x32 mm/kasan/report.c:506
kasan_report+0xe/0x20 mm/kasan/common.c:641
bitfill_aligned drivers/video/fbdev/core/sysfillrect.c:54 [inline]
bitfill_aligned+0x34b/0x410 drivers/video/fbdev/core/sysfillrect.c:25
sys_fillrect+0x415/0x7a0 drivers/video/fbdev/core/sysfillrect.c:291
drm_fb_helper_sys_fillrect+0x1c/0x190 drivers/gpu/drm/drm_fb_helper.c:719
bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232
fbcon_clear_margins+0x1de/0x240 drivers/video/fbdev/core/fbcon.c:1379
fbcon_switch+0xd1b/0x1740 drivers/video/fbdev/core/fbcon.c:2361
redraw_screen+0x2a8/0x770 drivers/tty/vt/vt.c:1008
fbcon_modechanged+0x5bd/0x780 drivers/video/fbdev/core/fbcon.c:2998
fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3045
fb_set_var+0xad0/0xd40 drivers/video/fbdev/core/fbmem.c:1056
do_fb_ioctl+0x390/0x7d0 drivers/video/fbdev/core/fbmem.c:1109
fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1185
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x433d29
Code: c4 18 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 0f 83 eb da fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff33d61508 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000433d29
RDX: 00000000200001c0 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 00000000006b2018 R08: 0000000000000000 R09: 00000000004002e0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401bc0
R13: 0000000000401c50 R14: 0000000000000000 R15: 0000000000000000

Memory state around the buggy address:

ffffc90009620f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc90009620f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90009621000: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
^
ffffc90009621080: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
ffffc90009621100: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
==================================================================

[Dmitry Vyukov]

On Tue, Mar 17, 2020 at 10:34 AM syzbot
<syzbot+e5fd3e...@syzkaller.appspotmail.com> wrote:
>
> syzbot has found a reproducer for the following crash on:
>
> HEAD commit: fb33c651 Linux 5.6-rc6
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=17dacd55e00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=9f894bd92023de02
> dashboard link: https://syzkaller.appspot.com/bug?extid=e5fd3e65515b48c02a30
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11b8ca75e00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=114800e5e00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+e5fd3e...@syzkaller.appspotmail.com

+George who may know what causes this

> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bug...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000a1c96505a109a31b%40google.com.