On Sun, 15 Dec 2019 12:35:09 -0800 > Hello, > > syzbot found the following crash on: > > HEAD commit: 07c4b9e9 Merge tag 'scsi-fixes' of git://git.kernel.org/pu.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=14b61f41e00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=79f79de2a27d3e3d > dashboard link: https://syzkaller.appspot.com/bug?extid=9116ecc1978ca3a12f43 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=119fa6b6e00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+9116ecc1978ca3a12f43@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KASAN: use-after-free in fbcon_cursor+0x4ef/0x660 > drivers/video/fbdev/core/fbcon.c:1380 > Read of size 2 at addr ffff8880959ff0cc by task syz-executor.0/10203 > > CPU: 1 PID: 10203 Comm: syz-executor.0 Not tainted 5.5.0-rc1-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+0x197/0x210 lib/dump_stack.c:118 > print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 > __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506 > kasan_report+0x12/0x20 mm/kasan/common.c:639 > __asan_report_load2_noabort+0x14/0x20 mm/kasan/generic_report.c:133 > fbcon_cursor+0x4ef/0x660 drivers/video/fbdev/core/fbcon.c:1380 > fbcon_scrolldelta+0x679/0x1220 drivers/video/fbdev/core/fbcon.c:2877 > fbcon_set_origin+0x43/0x50 drivers/video/fbdev/core/fbcon.c:2928 > set_origin+0xf3/0x400 drivers/tty/vt/vt.c:919 > vc_do_resize+0xacc/0x1460 drivers/tty/vt/vt.c:1264 > vc_resize+0x4d/0x60 drivers/tty/vt/vt.c:1304 > vt_ioctl+0x14bb/0x26d0 drivers/tty/vt/vt_ioctl.c:840 > tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 > 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: 0033:0x45a909 > Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f1a84ca0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a909 > RDX: 0000000020000000 RSI: 0000000000005609 RDI: 0000000000000003 > RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1a84ca16d4 > R13: 00000000004c7009 R14: 00000000004dd670 R15: 00000000ffffffff > > Allocated by task 9734: > save_stack+0x23/0x90 mm/kasan/common.c:72 > set_track mm/kasan/common.c:80 [inline] > __kasan_kmalloc mm/kasan/common.c:513 [inline] > __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486 > kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527 > __do_kmalloc mm/slab.c:3656 [inline] > __kmalloc+0x163/0x770 mm/slab.c:3665 > kmalloc include/linux/slab.h:561 [inline] > kzalloc include/linux/slab.h:670 [inline] > vc_do_resize+0x262/0x1460 drivers/tty/vt/vt.c:1187 > vc_resize+0x4d/0x60 drivers/tty/vt/vt.c:1304 > vt_ioctl+0x14bb/0x26d0 drivers/tty/vt/vt_ioctl.c:840 > tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 > 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 > > Freed by task 10203: > save_stack+0x23/0x90 mm/kasan/common.c:72 > set_track mm/kasan/common.c:80 [inline] > kasan_set_free_info mm/kasan/common.c:335 [inline] > __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474 > kasan_slab_free+0xe/0x10 mm/kasan/common.c:483 > __cache_free mm/slab.c:3426 [inline] > kfree+0x10a/0x2c0 mm/slab.c:3757 > vc_do_resize+0xa69/0x1460 drivers/tty/vt/vt.c:1261 > vc_resize+0x4d/0x60 drivers/tty/vt/vt.c:1304 > vt_ioctl+0x14bb/0x26d0 drivers/tty/vt/vt_ioctl.c:840 > tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 > 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 > > The buggy address belongs to the object at ffff8880959ff0c0 > which belongs to the cache kmalloc-32 of size 32 > The buggy address is located 12 bytes inside of > 32-byte region [ffff8880959ff0c0, ffff8880959ff0e0) > The buggy address belongs to the page: > page:ffffea0002567fc0 refcount:1 mapcount:0 mapping:ffff8880aa4001c0 > index:0xffff8880959fffc1 > raw: 00fffe0000000200 ffffea00027c7748 ffffea000276ee08 ffff8880aa4001c0 > raw: ffff8880959fffc1 ffff8880959ff000 000000010000003f 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8880959fef80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8880959ff000: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc > > ffff8880959ff080: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc > ^ > ffff8880959ff100: 00 01 fc fc fc fc fc fc fb fb fb fb fc fc fc fc > ffff8880959ff180: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc > ================================================================== Release old screen buffer after use. --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -1161,6 +1161,7 @@ static int vc_do_resize(struct tty_struc unsigned int new_cols, new_rows, new_row_size, new_screen_size; unsigned int user; unsigned short *newscreen; + unsigned short *oldscreen; struct uni_screen *new_uniscr = NULL; WARN_CONSOLE_UNLOCKED(); @@ -1258,10 +1259,11 @@ static int vc_do_resize(struct tty_struc if (new_scr_end > new_origin) scr_memsetw((void *)new_origin, vc->vc_video_erase_char, new_scr_end - new_origin); - kfree(vc->vc_screenbuf); + oldscreen = vc->vc_screenbuf; vc->vc_screenbuf = newscreen; vc->vc_screenbuf_size = new_screen_size; set_origin(vc); + kfree(oldscreen); /* do part of a reset_terminal() */ vc->vc_top = 0; _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
