On Tue, Jul 07, 2020 at 05:24:11PM +0200, Jan Kara wrote: > On Mon 06-07-20 08:42:24, syzbot wrote: > > syzbot found the following crash on: > > > > HEAD commit: 7cc2a8ea Merge tag 'block-5.8-2020-07-01' of git://git.ker.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=17644c05100000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=5ee23b9caef4e07a > > dashboard link: https://syzkaller.appspot.com/bug?extid=dec34b033b3479b9ef13 > > compiler: gcc (GCC) 10.1.0-syz 20200507 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1478a67b100000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+dec34b033b3479b9ef13@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > BUG: memory leak > > unreferenced object 0xffff888115db8480 (size 576): > > comm "systemd-udevd", pid 11037, jiffies 4295104591 (age 56.960s) > > hex dump (first 32 bytes): > > 00 04 00 00 00 00 00 00 80 fd e8 15 81 88 ff ff ................ > > a0 02 dd 20 81 88 ff ff b0 81 d0 09 81 88 ff ff ... ............ > > backtrace: > > [<00000000288c0066>] radix_tree_node_alloc.constprop.0+0xc1/0x140 lib/radix-tree.c:252 > > [<00000000f80ba6a7>] idr_get_free+0x231/0x3b0 lib/radix-tree.c:1505 > > [<00000000ec9ab938>] idr_alloc_u32+0x91/0x120 lib/idr.c:46 > > [<00000000aea98d29>] idr_alloc_cyclic+0x84/0x110 lib/idr.c:125 > > [<00000000dbad44a4>] inotify_add_to_idr fs/notify/inotify/inotify_user.c:365 [inline] > > [<00000000dbad44a4>] inotify_new_watch fs/notify/inotify/inotify_user.c:578 [inline] > > [<00000000dbad44a4>] inotify_update_watch+0x1af/0x2d0 fs/notify/inotify/inotify_user.c:617 > > [<00000000e141890d>] __do_sys_inotify_add_watch fs/notify/inotify/inotify_user.c:755 [inline] > > [<00000000e141890d>] __se_sys_inotify_add_watch fs/notify/inotify/inotify_user.c:698 [inline] > > [<00000000e141890d>] __x64_sys_inotify_add_watch+0x12f/0x180 fs/notify/inotify/inotify_user.c:698 > > [<00000000d872d7cc>] do_syscall_64+0x4c/0xe0 arch/x86/entry/common.c:359 > > [<000000005c62d8da>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > I've been looking into this for a while and I don't think this is related > to inotify at all. Firstly the reproducer looks totally benign: > > prlimit64(0x0, 0xe, &(0x7f0000000280)={0x9, 0x8d}, 0x0) > sched_setattr(0x0, &(0x7f00000000c0)={0x38, 0x2, 0x0, 0x0, 0x9}, 0x0) > vmsplice(0xffffffffffffffff, 0x0, 0x0, 0x0) > perf_event_open(0x0, 0x0, 0xffffffffffffffff, 0xffffffffffffffff, 0x0) > clone(0x20000103, 0x0, 0xfffffffffffffffe, 0x0, 0xffffffffffffffff) > syz_mount_image$vfat(0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0) > > So we seem to set SCHED_RR class and prio 9 to itself, the rest of syscalls > seem to be invalid and should fail. Secondly, the kernel log shows that we > hit OOM killer frequently and after one of these kills, many leaked objects > (among them this radix tree node from inotify idr) are reported. I'm not > sure if it could be the leak detector getting confused (e.g. because it got > ENOMEM at some point) or something else... Catalin, any idea? Just wondering, if this leak is reproducible, could we have some condition where inotify_remove_from_idr() is not called in case of a forced exit triggered by the OOM kill? Also, can the leak be reproduced without the OOM? -- Catalin
