================================================================== BUG: KASAN: slab-out-of-bounds in __fb_pad_aligned_buffer include/linux/fb.h:654 [inline] BUG: KASAN: slab-out-of-bounds in bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline] BUG: KASAN: slab-out-of-bounds in bit_putcs+0xbb6/0xd20 drivers/video/fbdev/core/bitblit.c:185 Read of size 1 at addr ffff888096e50dc0 by task syz-executor.4/28513 CPU: 0 PID: 28513 Comm: syz-executor.4 Not tainted 5.9.0-rc5-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+0x198/0x1fd lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 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+0xbb6/0xd20 drivers/video/fbdev/core/bitblit.c:185 fbcon_putcs+0x35a/0x450 drivers/video/fbdev/core/fbcon.c:1308 con_flush drivers/tty/vt/vt.c:2575 [inline] do_con_write+0xb6b/0x1dd0 drivers/tty/vt/vt.c:2905 con_write+0x22/0xb0 drivers/tty/vt/vt.c:3250 process_output_block drivers/tty/n_tty.c:595 [inline] n_tty_write+0x3ce/0xf80 drivers/tty/n_tty.c:2333 do_tty_write drivers/tty/tty_io.c:962 [inline] tty_write+0x4d9/0x870 drivers/tty/tty_io.c:1046 do_loop_readv_writev fs/read_write.c:737 [inline] do_loop_readv_writev fs/read_write.c:721 [inline] do_iter_write+0x489/0x670 fs/read_write.c:1020 vfs_writev+0x1aa/0x2e0 fs/read_write.c:1091 do_writev+0x139/0x300 fs/read_write.c:1134 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5f9 Code: 5d b4 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 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f8dd55efc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 0000000000039c40 RCX: 000000000045d5f9 RDX: 0000000000000001 RSI: 0000000020001480 RDI: 0000000000000006 RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007fffbf27006f R14: 00007f8dd55f09c0 R15: 000000000118cf4c Allocated by task 20974: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461 __do_kmalloc mm/slab.c:3655 [inline] __kmalloc+0x1b0/0x360 mm/slab.c:3664 kmalloc include/linux/slab.h:559 [inline] fbcon_set_font+0x363/0x9b0 drivers/video/fbdev/core/fbcon.c:2496 con_font_set drivers/tty/vt/vt.c:4663 [inline] con_font_op+0xd26/0x1140 drivers/tty/vt/vt.c:4728 vt_io_ioctl drivers/tty/vt/vt_ioctl.c:595 [inline] vt_ioctl+0x1ce7/0x2e90 drivers/tty/vt/vt_ioctl.c:856 tty_ioctl+0x1019/0x15f0 drivers/tty/tty_io.c:2656 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff888096e50000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 3520 bytes inside of 4096-byte region [ffff888096e50000, ffff888096e51000) The buggy address belongs to the page: page:00000000afe6f71d refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x96e50 head:00000000afe6f71d order:1 compound_mapcount:0 flags: 0xfffe0000010200(slab|head) raw: 00fffe0000010200 ffffea000216d208 ffffea00029d9e88 ffff8880aa040900 raw: 0000000000000000 ffff888096e50000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888096e50c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888096e50d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888096e50d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff888096e50e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888096e50e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================