On Fri, Feb 16, 2024 at 03:30:47PM +0800, Edward Adam Davis wrote: > [Syzbot reported] > BUG: KASAN: slab-use-after-free in pvr2_context_set_notify+0x2c4/0x310 drivers/media/usb/pvrusb2/pvrusb2-context.c:35 > Read of size 4 at addr ffff888113aeb0d8 by task kworker/1:1/26 > > CPU: 1 PID: 26 Comm: kworker/1:1 Not tainted 6.8.0-rc1-syzkaller-00046-gf1a27f081c1f #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 > Workqueue: usb_hub_wq hub_event > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 > print_address_description mm/kasan/report.c:377 [inline] > print_report+0xc4/0x620 mm/kasan/report.c:488 > kasan_report+0xda/0x110 mm/kasan/report.c:601 > pvr2_context_set_notify+0x2c4/0x310 drivers/media/usb/pvrusb2/pvrusb2-context.c:35 > pvr2_context_notify drivers/media/usb/pvrusb2/pvrusb2-context.c:95 [inline] > pvr2_context_disconnect+0x94/0xb0 drivers/media/usb/pvrusb2/pvrusb2-context.c:272 > > Freed by task 906: > kasan_save_stack+0x33/0x50 mm/kasan/common.c:47 > kasan_save_track+0x14/0x30 mm/kasan/common.c:68 > kasan_save_free_info+0x3f/0x60 mm/kasan/generic.c:640 > poison_slab_object mm/kasan/common.c:241 [inline] > __kasan_slab_free+0x106/0x1b0 mm/kasan/common.c:257 > kasan_slab_free include/linux/kasan.h:184 [inline] > slab_free_hook mm/slub.c:2121 [inline] > slab_free mm/slub.c:4299 [inline] > kfree+0x105/0x340 mm/slub.c:4409 > pvr2_context_check drivers/media/usb/pvrusb2/pvrusb2-context.c:137 [inline] > pvr2_context_thread_func+0x69d/0x960 drivers/media/usb/pvrusb2/pvrusb2-context.c:158 > > [Analyze] > Task A set disconnect_flag = !0, which resulted in Task B's condition being met > and releasing mp, leading to this issue. > > [Fix] > Place the disconnect_flag assignment operation after all code in pvr2_context_disconnect() > to avoid this issue. > > Reported-and-tested-by: syzbot+ce750e124675d4599449@xxxxxxxxxxxxxxxxxxxxxxxxx > Signed-off-by: Edward Adam Davis <eadavis@xxxxxx> What commit id does this fix? And should it be cc: stable as well? thanks, greg k-h
