This is a note to let you know that I've just added the patch titled
bpf: Fix umd memory leak in copy_process()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-fix-umd-memory-leak-in-copy_process.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a6506e621791862eefd30b6e688a6260f46366a2
Author: Zqiang <qiang.zhang@xxxxxxxxxxxxx>
Date: Wed Mar 17 11:09:15 2021 +0800
bpf: Fix umd memory leak in copy_process()
[ Upstream commit f60a85cad677c4f9bb4cadd764f1d106c38c7cf8 ]
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:
[<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 released.
Fixes: d71fa5c9763c ("bpf: Add kernel module with user mode driver that populates bpffs.")
Reported-by: syzbot+44908bb56d2bfe56b28e@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Zqiang <qiang.zhang@xxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210317030915.2865-1-qiang.zhang@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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..53736e52c1df 100644
--- a/kernel/bpf/preload/bpf_preload_kern.c
+++ b/kernel/bpf/preload/bpf_preload_kern.c
@@ -60,9 +60,12 @@ static int finish(void)
&magic, sizeof(magic), &pos);
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 +83,18 @@ 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..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
