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BUG: KASAN: use-after-free in __fb_pad_aligned_buffer include/linux/fb.h:654 [inline]
BUG: KASAN: use-after-free in bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
BUG: KASAN: use-after-free in bit_putcs+0x103a/0x1bf0 drivers/video/fbdev/core/bitblit.c:185
Read of size 1 at addr ffff88809490a408 by task syz-executor.4/12781

CPU: 0 PID: 12781 Comm: syz-executor.4 Not tainted 5.9.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d6/0x29e lib/dump_stack.c:118
 print_address_description+0x66/0x620 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report+0x132/0x1d0 mm/kasan/report.c:530
 __fb_pad_aligned_buffer include/linux/fb.h:654 [inline]
 bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
 bit_putcs+0x103a/0x1bf0 drivers/video/fbdev/core/bitblit.c:185
 fbcon_putcs+0x790/0xaf0 drivers/video/fbdev/core/fbcon.c:1308
 con_flush drivers/tty/vt/vt.c:2575 [inline]
 do_con_write+0x2853/0xd580 drivers/tty/vt/vt.c:2905
 con_write+0x20/0x40 drivers/tty/vt/vt.c:3250
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0xcbf/0x1170 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x593/0x940 drivers/tty/tty_io.c:1046
 vfs_write+0x2d3/0xd10 fs/read_write.c:576
 ksys_write+0x11b/0x220 fs/read_write.c:631
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45e179
Code: 3d b2 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 0b b2 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ff8fd2d5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000038f40 RCX: 000000000045e179
RDX: 0000000000001006 RSI: 00000000200002c0 RDI: 0000000000000004
RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffe44bdd46f R14: 00007ff8fd2d69c0 R15: 000000000118cf4c

Allocated by task 3913:
 kasan_save_stack mm/kasan/common.c:48 [inline]
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc+0x100/0x130 mm/kasan/common.c:461
 kmem_cache_alloc_trace+0x1e4/0x2e0 mm/slab.c:3550
 kmalloc include/linux/slab.h:554 [inline]
 kzalloc include/linux/slab.h:666 [inline]
 kernfs_fop_open+0x3c5/0xc30 fs/kernfs/file.c:647
 do_dentry_open+0x7c8/0x1010 fs/open.c:817
 do_open fs/namei.c:3251 [inline]
 path_openat+0x2794/0x3840 fs/namei.c:3368
 do_filp_open+0x191/0x3a0 fs/namei.c:3395
 do_sys_openat2+0x463/0x830 fs/open.c:1168
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_open fs/open.c:1192 [inline]
 __se_sys_open fs/open.c:1188 [inline]
 __x64_sys_open+0x1af/0x1e0 fs/open.c:1188
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88809490a400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes inside of
 512-byte region [ffff88809490a400, ffff88809490a600)
The buggy address belongs to the page:
page:00000000ffdc9cea refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88809490a400 pfn:0x9490a
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002659ec8 ffffea00027c0c48 ffff8880aa440600
raw: ffff88809490a400 ffff88809490a000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809490a300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809490a380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809490a400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88809490a480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809490a500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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