From: Zqiang <[email protected]>
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: [email protected]
Signed-off-by: Zqiang <[email protected]>
---
v1->v2:
Judge whether the pointer variable tgid is valid.
kernel/bpf/preload/bpf_preload_kern.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/kernel/bpf/preload/bpf_preload_kern.c b/kernel/bpf/preload/bpf_preload_kern.c
index 79c5772465f1..5009875f01d3 100644
--- a/kernel/bpf/preload/bpf_preload_kern.c
+++ b/kernel/bpf/preload/bpf_preload_kern.c
@@ -4,6 +4,7 @@
#include <linux/module.h>
#include <linux/pid.h>
#include <linux/fs.h>
+#include <linux/file.h>
#include <linux/sched/signal.h>
#include "bpf_preload.h"
@@ -20,6 +21,14 @@ static struct bpf_preload_ops umd_ops = {
.owner = THIS_MODULE,
};
+static void bpf_preload_umh_cleanup(struct umd_info *info)
+{
+ fput(info->pipe_to_umh);
+ fput(info->pipe_from_umh);
+ put_pid(info->tgid);
+ info->tgid = NULL;
+}
+
static int preload(struct bpf_preload_info *obj)
{
int magic = BPF_PRELOAD_START;
@@ -61,8 +70,10 @@ 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));
+ bpf_preload_umh_cleanup(&umd_ops.info);
+ }
return 0;
}
@@ -80,10 +91,15 @@ 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));
+ bpf_preload_umh_cleanup(&umd_ops.info);
+ }
umd_unload_blob(&umd_ops.info);
}
late_initcall(load_umd);
--
2.17.1
Hello Alexei Starovoitov Daniel Borkmann
Please review this patch.
Thanks
Qiang
________________________________________
??????: Zhang, Qiang <[email protected]>
????ʱ??: 2021??3??15?? 16:53
?ռ???: [email protected]; [email protected]; [email protected]
????: [email protected]; [email protected]; [email protected]; [email protected]; Zhang, Qiang
????: [PATCH v2] bpf: Fix memory leak in copy_process()
From: Zqiang <[email protected]>
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: [email protected]
Signed-off-by: Zqiang <[email protected]>
---
v1->v2:
Judge whether the pointer variable tgid is valid.
kernel/bpf/preload/bpf_preload_kern.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/kernel/bpf/preload/bpf_preload_kern.c b/kernel/bpf/preload/bpf_preload_kern.c
index 79c5772465f1..5009875f01d3 100644
--- a/kernel/bpf/preload/bpf_preload_kern.c
+++ b/kernel/bpf/preload/bpf_preload_kern.c
@@ -4,6 +4,7 @@
#include <linux/module.h>
#include <linux/pid.h>
#include <linux/fs.h>
+#include <linux/file.h>
#include <linux/sched/signal.h>
#include "bpf_preload.h"
@@ -20,6 +21,14 @@ static struct bpf_preload_ops umd_ops = {
.owner = THIS_MODULE,
};
+static void bpf_preload_umh_cleanup(struct umd_info *info)
+{
+ fput(info->pipe_to_umh);
+ fput(info->pipe_from_umh);
+ put_pid(info->tgid);
+ info->tgid = NULL;
+}
+
static int preload(struct bpf_preload_info *obj)
{
int magic = BPF_PRELOAD_START;
@@ -61,8 +70,10 @@ 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));
+ bpf_preload_umh_cleanup(&umd_ops.info);
+ }
return 0;
}
@@ -80,10 +91,15 @@ 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));
+ bpf_preload_umh_cleanup(&umd_ops.info);
+ }
umd_unload_blob(&umd_ops.info);
}
late_initcall(load_umd);
--
2.17.1
On Tue, Mar 16, 2021 at 4:29 AM Zhang, Qiang <[email protected]> wrote:
>
> Hello Alexei Starovoitov Daniel Borkmann
> Please review this patch.
Please don't top post.
On 3/15/21 9:58 AM, [email protected] wrote:
> From: Zqiang <[email protected]>
nit: I presume it should be s/Zqiang/Qiang Zhang/ as real name for 'From'
instead of abbreviation?
> 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: [email protected]
> Signed-off-by: Zqiang <[email protected]>
nit: Ditto
> ---
> v1->v2:
> Judge whether the pointer variable tgid is valid.
>
> kernel/bpf/preload/bpf_preload_kern.c | 24 ++++++++++++++++++++----
> 1 file changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/preload/bpf_preload_kern.c b/kernel/bpf/preload/bpf_preload_kern.c
> index 79c5772465f1..5009875f01d3 100644
> --- a/kernel/bpf/preload/bpf_preload_kern.c
> +++ b/kernel/bpf/preload/bpf_preload_kern.c
> @@ -4,6 +4,7 @@
> #include <linux/module.h>
> #include <linux/pid.h>
> #include <linux/fs.h>
> +#include <linux/file.h>
> #include <linux/sched/signal.h>
> #include "bpf_preload.h"
>
> @@ -20,6 +21,14 @@ static struct bpf_preload_ops umd_ops = {
> .owner = THIS_MODULE,
> };
>
> +static void bpf_preload_umh_cleanup(struct umd_info *info)
> +{
> + fput(info->pipe_to_umh);
> + fput(info->pipe_from_umh);
> + put_pid(info->tgid);
> + info->tgid = NULL;
> +}
The above is pretty much a reimplementation of ...
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;
}
}
... so if there are ever changes to umd_cleanup() for additional resource
cleanup, we'd be missing those easily in bpf_preload_umh_cleanup(). I'd
suggest to refactor a common helper inside kernel/usermode_driver.c that
is then exported as symbol which the driver here can use.
> static int preload(struct bpf_preload_info *obj)
> {
> int magic = BPF_PRELOAD_START;
> @@ -61,8 +70,10 @@ 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));
> + bpf_preload_umh_cleanup(&umd_ops.info);
> + }
> return 0;
> }
>
> @@ -80,10 +91,15 @@ 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));
> + bpf_preload_umh_cleanup(&umd_ops.info);
> + }
> umd_unload_blob(&umd_ops.info);
> }
> late_initcall(load_umd);
>