From f60a85cad677c4f9bb4cadd764f1d106c38c7cf8 Mon Sep 17 00:00:00 2001 From: Zqiang Date: Wed, 17 Mar 2021 11:09:15 +0800 Subject: bpf: Fix umd memory leak in copy_process() The syzbot reported a memleak as follows: BUG: memory leak unreferenced object 0xffff888101b41d00 (size 120): comm "kworker/u4:0", pid 8, jiffies 4294944270 (age 12.780s) backtrace: [] alloc_pid+0x66/0x560 [] copy_process+0x1465/0x25e0 [] kernel_clone+0xf3/0x670 [] kernel_thread+0x61/0x80 [] call_usermodehelper_exec_work [] call_usermodehelper_exec_work+0xc4/0x120 [] process_one_work+0x2c9/0x600 [] worker_thread+0x59/0x5d0 [] kthread+0x178/0x1b0 [] ret_from_fork+0x1f/0x30 unreferenced object 0xffff888110ef5c00 (size 232): comm "kworker/u4:0", pid 8414, jiffies 4294944270 (age 12.780s) backtrace: [] kmem_cache_zalloc [] __alloc_file+0x1f/0xf0 [] alloc_empty_file+0x69/0x120 [] alloc_file+0x33/0x1b0 [] alloc_file_pseudo+0xb2/0x140 [] create_pipe_files+0x138/0x2e0 [] umd_setup+0x33/0x220 [] call_usermodehelper_exec_async+0xb4/0x1b0 [] ret_from_fork+0x1f/0x30 After the UMD process exits, the pipe_to_umh/pipe_from_umh and tgid need to be released. Fixes: d71fa5c9763c ("bpf: Add kernel module with user mode driver that populates bpffs.") Reported-by: syzbot+44908bb56d2bfe56b28e@syzkaller.appspotmail.com Signed-off-by: Zqiang Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20210317030915.2865-1-qiang.zhang@windriver.com --- kernel/usermode_driver.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) (limited to 'kernel/usermode_driver.c') diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c index 0b35212ffc3d..bb7bb3b478ab 100644 --- a/kernel/usermode_driver.c +++ b/kernel/usermode_driver.c @@ -139,13 +139,22 @@ static void umd_cleanup(struct subprocess_info *info) struct umd_info *umd_info = info->data; /* cleanup if umh_setup() was successful but exec failed */ - if (info->retval) { - fput(umd_info->pipe_to_umh); - fput(umd_info->pipe_from_umh); - put_pid(umd_info->tgid); - umd_info->tgid = NULL; - } + if (info->retval) + umd_cleanup_helper(umd_info); +} + +/** + * umd_cleanup_helper - release the resources which were allocated in umd_setup + * @info: information about usermode driver + */ +void umd_cleanup_helper(struct umd_info *info) +{ + fput(info->pipe_to_umh); + fput(info->pipe_from_umh); + put_pid(info->tgid); + info->tgid = NULL; } +EXPORT_SYMBOL_GPL(umd_cleanup_helper); /** * fork_usermode_driver - fork a usermode driver -- cgit v1.2.3