From: Zqiang
The syzbot report a memleak follow:
BUG: memory leak
unreferenced object 0x888101b41d00 (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 0x888110ef5c00 (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 release.
Fixes: d71fa5c9763c ("bpf: Add kernel module with user mode driver that
populates bpffs.")
Reported-by: syzbot+44908bb56d2bfe56b...@syzkaller.appspotmail.com
Signed-off-by: Zqiang
---
v1->v2:
Judge whether the pointer variable tgid is valid.
v2->v3:
Add common umd_cleanup_helper() and exported as
symbol which the driver here can use.
include/linux/usermode_driver.h | 1 +
kernel/bpf/preload/bpf_preload_kern.c | 15 +++
kernel/usermode_driver.c | 18 ++
3 files changed, 26 insertions(+), 8 deletions(-)
diff --git a/include/linux/usermode_driver.h b/include/linux/usermode_driver.h
index 073a9e0ec07d..ad970416260d 100644
--- a/include/linux/usermode_driver.h
+++ b/include/linux/usermode_driver.h
@@ -14,5 +14,6 @@ struct umd_info {
int umd_load_blob(struct umd_info *info, const void *data, size_t len);
int umd_unload_blob(struct umd_info *info);
int fork_usermode_driver(struct umd_info *info);
+void umd_cleanup_helper(struct umd_info *info);
#endif /* __LINUX_USERMODE_DRIVER_H__ */
diff --git a/kernel/bpf/preload/bpf_preload_kern.c
b/kernel/bpf/preload/bpf_preload_kern.c
index 79c5772465f1..356c4ca4f530 100644
--- a/kernel/bpf/preload/bpf_preload_kern.c
+++ b/kernel/bpf/preload/bpf_preload_kern.c
@@ -61,8 +61,10 @@ static int finish(void)
if (n != sizeof(magic))
return -EPIPE;
tgid = umd_ops.info.tgid;
- wait_event(tgid->wait_pidfd, thread_group_exited(tgid));
- umd_ops.info.tgid = NULL;
+ if (tgid) {
+ wait_event(tgid->wait_pidfd, thread_group_exited(tgid));
+ umd_cleanup_helper(&umd_ops.info);
+ }
return 0;
}
@@ -80,10 +82,15 @@ static int __init load_umd(void)
static void __exit fini_umd(void)
{
+ struct pid *tgid;
bpf_preload_ops = NULL;
/* kill UMD in case it's still there due to earlier error */
- kill_pid(umd_ops.info.tgid, SIGKILL, 1);
- umd_ops.info.tgid = NULL;
+ tgid = umd_ops.info.tgid;
+ if (tgid) {
+ kill_pid(tgid, SIGKILL, 1);
+ wait_event(tgid->wait_pidfd, thread_group_exited(tgid));
+ umd_cleanup_helper(&umd_ops.info);
+ }
umd_unload_blob(&umd_ops.info);
}
late_initcall(load_umd);
diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c
index 0b35212ffc3d..6372deae27a0 100644
--- a/kernel/usermode_driver.c
+++ b/kernel/usermode_driver.c
@@ -140,13 +140,23 @@ static void umd_cleanup(struct subprocess_info *info)
/* 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;
+ umd_cleanup_helper(umd_info);
}
}
+/**
+ * umd_cleanup_helper - release the resources which 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
* @info: information about usermode driver (shouldn't be NULL)
--
2.17.1
