Hi,
We found a potential memory leak in bpf_timer in v5.15.26 using a
customized syzkaller for fuzzing bpf runtime. It can happen when
an arraymap is being released. An entry that has been checked by
bpf_timer_cancel_and_free() can again be initialized by bpf_timer_init().
Since both paths are almost identical between v5.15 and net-next,
I suspect this problem still exists. Below are kmemleak report and
some additional printks I inserted.
[ 1364.081694] array_map_free_timers map:0xffffc900005a9000
[ 1364.081730] ____bpf_timer_init map:0xffffc900005a9000
timer:0xffff888001ab4080
*no bpf_timer_cancel_and_free that will kfree struct bpf_hrtimer*
at 0xffff888001ab4080 is called
[ 1383.907869] kmemleak: 1 new suspected memory leaks (see
/sys/kernel/debug/kmemleak)
BUG: memory leak
unreferenced object 0xffff888001ab4080 (size 96):
comm "sshd", pid 279, jiffies 4295233126 (age 29.952s)
hex dump (first 32 bytes):
80 40 ab 01 80 88 ff ff 00 00 00 00 00 00 00 00 .@..............
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<000000009d018da0>] bpf_map_kmalloc_node+0x89/0x1a0
[<00000000ebcb33fc>] bpf_timer_init+0x177/0x320
[<00000000fb7e90bf>] 0xffffffffc02a0358
[<000000000c89ec4f>] __cgroup_bpf_run_filter_skb+0xcbf/0x1110
[<00000000fd663fc0>] ip_finish_output+0x13d/0x1f0
[<00000000acb3205c>] ip_output+0x19b/0x310
[<000000006b584375>] __ip_queue_xmit+0x182e/0x1ed0
[<00000000b921b07e>] __tcp_transmit_skb+0x2b65/0x37f0
[<0000000026104b23>] tcp_write_xmit+0xf19/0x6290
[<000000006dc71bc5>] __tcp_push_pending_frames+0xaf/0x390
[<00000000251b364a>] tcp_push+0x452/0x6d0
[<000000008522b7d3>] tcp_sendmsg_locked+0x2567/0x3030
[<0000000038c644d2>] tcp_sendmsg+0x30/0x50
[<000000009fe3413f>] inet_sendmsg+0xba/0x140
[<0000000034d78039>] sock_sendmsg+0x13d/0x190
[<00000000f55b8db6>] sock_write_iter+0x296/0x3d0
Thanks,
Hsin-Wei (Amery)
