Re: [PATCH v3] bpf: Fix memory leak in copy_process()

On 3/17/21 4:09 AM, qiang.zhang@windriver.com wrote:

From: Zqiang <redacted>

The syzbot report a memleak follow:
BUG: memory leak
unreferenced object 0xffff888101b41d00 (size 120):
   comm "kworker/u4:0", pid 8, jiffies 4294944270 (age 12.780s)
   backtrace:
     [<ffffffff8125dc56>] alloc_pid+0x66/0x560
     [<ffffffff81226405>] copy_process+0x1465/0x25e0
     [<ffffffff81227943>] kernel_clone+0xf3/0x670
     [<ffffffff812281a1>] kernel_thread+0x61/0x80
     [<ffffffff81253464>] call_usermodehelper_exec_work
     [<ffffffff81253464>] call_usermodehelper_exec_work+0xc4/0x120
     [<ffffffff812591c9>] process_one_work+0x2c9/0x600
     [<ffffffff81259ab9>] worker_thread+0x59/0x5d0
     [<ffffffff812611c8>] kthread+0x178/0x1b0
     [<ffffffff8100227f>] ret_from_fork+0x1f/0x30

unreferenced object 0xffff888110ef5c00 (size 232):
   comm "kworker/u4:0", pid 8414, jiffies 4294944270 (age 12.780s)
   backtrace:
     [<ffffffff8154a0cf>] kmem_cache_zalloc
     [<ffffffff8154a0cf>] __alloc_file+0x1f/0xf0
     [<ffffffff8154a809>] alloc_empty_file+0x69/0x120
     [<ffffffff8154a8f3>] alloc_file+0x33/0x1b0
     [<ffffffff8154ab22>] alloc_file_pseudo+0xb2/0x140
     [<ffffffff81559218>] create_pipe_files+0x138/0x2e0
     [<ffffffff8126c793>] umd_setup+0x33/0x220
     [<ffffffff81253574>] call_usermodehelper_exec_async+0xb4/0x1b0
     [<ffffffff8100227f>] ret_from_fork+0x1f/0x30

after the UMD process exits, the pipe_to_umh/pipe_from_umh and tgid
need to be release.

Fixes: d71fa5c9763c ("bpf: Add kernel module with user mode driver that populates bpffs.")
Reported-by: syzbot+44908bb56d2bfe56b28e@syzkaller.appspotmail.com
Signed-off-by: Zqiang <redacted>

Applied to bpf, thanks (also did minor style fixups to fix kernel style)!