在 2024/10/10 22:14, Trond Myklebust 写道:
On Thu, 2024-10-10 at 21:40 +0800, yangerkun wrote:
在 2024/10/9 22:54, Trond Myklebust 写道:
On Wed, 2024-10-09 at 11:02 +0800, yangerkun wrote:
Hi,
Ping for this patch...
在 2024/9/29 9:45, yangerkun 写道:
在 2024/9/29 9:38, yangerkun 写道:
在 2024/9/28 4:58, Anna Schumaker 写道:
Hi Yang,
On 9/26/24 2:12 AM, Yang Erkun wrote:
From: Yang Erkun <yangerkun@xxxxxxxxxx>
Two threads that work with the same cred try to open
different files
concurrently, they will utilize the same
nfs4_state_owner.
And in order
to sequential open request send to server, the second
task
will fall
into RPC_TASK_QUEUED in nfs_wait_on_sequence since there
is
already one
work doing the open operation. Furthermore, the second
task
will wait
until the first task completes its work, call
rpc_wake_up_queued_task in
nfs_release_seqid to wake up the second task, allowing it
to
complete
the remaining open operation.
The preceding logic does not cause any problems under
normal
circumstances. However, when once we force an unmount
using
`umount
-f`,
the function nfs_umount_begin attempts to kill all tasks
by
calling
rpc_signal_task. This help wake up the second task, but
it
sets the
status to -ERESTARTSYS. This status prevents
`nfs4_open_release` from
calling `nfs4_opendata_to_nfs4_state`. Consequently,
while
the second
task will be freed, the original tasks will still exist
in
sequence->list(see nfs_release_seqid). Latter, when the
first
thread
calls nfs_release_seqid and attempts to wake up the
second
task, it
will
trigger the uaf.
To resolve this issue, ensure rpc_task will remove it
from
sequence->list by adding nfs_release_seqid in
nfs4_open_release.
=========================================================
====
=====
BUG: KASAN: slab-use-after-free in
rpc_wake_up_queued_task+0xbb/0xc0
Read of size 8 at addr ff11000007639930 by task bash/792
CPU: 0 UID: 0 PID: 792 Comm: bash Tainted: G B W
6.11.0-09960-gd10b58fe53dc-dirty #10
Tainted: [B]=BAD_PAGE, [W]=WARN
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS
1.16.1-2.fc37 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0xa3/0x120
print_address_description.constprop.0+0x63/0x510
print_report+0xf5/0x360
kasan_report+0xd9/0x140
__asan_report_load8_noabort+0x24/0x40
rpc_wake_up_queued_task+0xbb/0xc0
nfs_release_seqid+0x1e1/0x2f0
nfs_free_seqid+0x1a/0x40
nfs4_opendata_free+0xc6/0x3e0
_nfs4_do_open.isra.0+0xbe3/0x1380
nfs4_do_open+0x28b/0x620
nfs4_atomic_open+0x2c6/0x3a0
nfs_atomic_open+0x4f8/0x1180
atomic_open+0x186/0x4e0
lookup_open.isra.0+0x3e7/0x15b0
open_last_lookups+0x85d/0x1260
path_openat+0x151/0x7b0
do_filp_open+0x1e0/0x310
do_sys_openat2+0x178/0x1f0
do_sys_open+0xa2/0x100
__x64_sys_openat+0xa8/0x120
x64_sys_call+0x2507/0x4540
do_syscall_64+0xa7/0x240
entry_SYSCALL_64_after_hwframe+0x76/0x7e
...
Allocated by task 767:
kasan_save_stack+0x3b/0x70
kasan_save_track+0x1c/0x40
kasan_save_alloc_info+0x44/0x70
__kasan_slab_alloc+0xaf/0xc0
kmem_cache_alloc_noprof+0x1e0/0x4f0
rpc_new_task+0xe7/0x220
rpc_run_task+0x27/0x7d0
nfs4_run_open_task+0x477/0x810
_nfs4_proc_open+0xc0/0x6d0
_nfs4_open_and_get_state+0x178/0xc50
_nfs4_do_open.isra.0+0x47f/0x1380
nfs4_do_open+0x28b/0x620
nfs4_atomic_open+0x2c6/0x3a0
nfs_atomic_open+0x4f8/0x1180
atomic_open+0x186/0x4e0
lookup_open.isra.0+0x3e7/0x15b0
open_last_lookups+0x85d/0x1260
path_openat+0x151/0x7b0
do_filp_open+0x1e0/0x310
do_sys_openat2+0x178/0x1f0
do_sys_open+0xa2/0x100
__x64_sys_openat+0xa8/0x120
x64_sys_call+0x2507/0x4540
do_syscall_64+0xa7/0x240
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Freed by task 767:
kasan_save_stack+0x3b/0x70
kasan_save_track+0x1c/0x40
kasan_save_free_info+0x43/0x80
__kasan_slab_free+0x4f/0x90
kmem_cache_free+0x199/0x4f0
mempool_free_slab+0x1f/0x30
mempool_free+0xdf/0x3d0
rpc_free_task+0x12d/0x180
rpc_final_put_task+0x10e/0x150
rpc_do_put_task+0x63/0x80
rpc_put_task+0x18/0x30
nfs4_run_open_task+0x4f4/0x810
_nfs4_proc_open+0xc0/0x6d0
_nfs4_open_and_get_state+0x178/0xc50
_nfs4_do_open.isra.0+0x47f/0x1380
nfs4_do_open+0x28b/0x620
nfs4_atomic_open+0x2c6/0x3a0
nfs_atomic_open+0x4f8/0x1180
atomic_open+0x186/0x4e0
lookup_open.isra.0+0x3e7/0x15b0
open_last_lookups+0x85d/0x1260
path_openat+0x151/0x7b0
do_filp_open+0x1e0/0x310
do_sys_openat2+0x178/0x1f0
do_sys_open+0xa2/0x100
__x64_sys_openat+0xa8/0x120
x64_sys_call+0x2507/0x4540
do_syscall_64+0xa7/0x240
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Once I apply this patch I'm seeing my client hang when
running
xfstests generic/451 with NFS v4.0. I was wondering if you
could
check if you see the same hang, and please fix it if so?
I have try to reproduce this with kernel commit:
Forget to say, add this patch too...
commit abf2050f51fdca0fd146388f83cddd95a57a008d
Merge: 9ab27b018649 81ee62e8d09e
Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Mon Sep 23 15:27:58 2024 -0700
Merge tag 'media/v6.12-1' of
git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-
media
And for nfs4.0/nfs4.1, all seems ok now...
Can you provide more info about the 'hang' you meet now?
Thanks,
Anna
Fixes: 24ac23ab88df ("NFSv4: Convert open() into an
asynchronous RPC
call")
Signed-off-by: Yang Erkun <yangerkun@xxxxxxxxxx>
---
fs/nfs/nfs4proc.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b8ffbe52ba15..4685621ba469 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2603,6 +2603,7 @@ static void nfs4_open_release(void
*calldata)
struct nfs4_opendata *data = calldata;
struct nfs4_state *state = NULL;
+ nfs_release_seqid(data->o_arg.seqid);
/* If this request hasn't been cancelled, do
nothing */
if (!data->cancelled)
goto out_free;
If the OPEN was successful, but asked us to confirm the sequence
id, we
can end up releasing the sequence before we've been able to call
open_confirm if we do the above. I suspect this is why Anna is
seeing
the hang when running xfstests.
I think we rather want to check if (task->tk_status != 0 && !data-
rpc_done) before calling nfs_release_seqid() above, since that
might
correspond to the case where we interrupted the RPC call before it
gets
to the front of the list, but will never correspond to the case
where
we need to confirm the sequence.
The logic of this place is a little complicated for me. I'd like to
simplify it:
Actually, for the normal case, we no need call nfs_release_seqid
here.
The second task will wait until the first task completes its work,
call
rpc_wake_up_queued_task in
nfs_release_seqid(_nfs4_do_open->nfs4_opendata_put-
nfs4_opendata_free->_,
and the first rpc_task already be freed in nfs4_run_open_task) to
wake
up the second task, allowing it to complete the remaining open
operation. So, no use-after-free will happen.
Based on this, we should only call nfs_release_seqid for the abnormal
case:
- nfs4_opendata->cancelled == true: will return directly in
_nfs4_proc_open
This test is not needed. The question of whether or not the caller is
still waiting for the RPC call to complete is irrelevant to the problem
at hand, and just adds unnecessary testing overhead for the 99.9% case
where the OPEN is successful and the caller is waiting to complete the
call.
Yes, agree.
- **or** nfs4_opendata->rpc_status != 0: the status will be the
return value for nfs4_run_open_task, then _nfs4_proc_open will return
directly
This test is relevant. If the RPC call is interrupted, then it might
have happened while we were waiting to be given the sequence lock.
Yes, agree.
- **or** nfs4_opendata->rpc_done != true: _nfs4_proc_open will
return directly
This test is relevant, but only in conjunction with the test for -
rpc_status != 0.
If ->rpc_status == 0, then we know that we already hold the sequence
lock and so there is no danger of the use-after-free occurring.
Please see the latter detail.
Furthermore, we want to keep holding that lock so that we can safely
call nfs4_try_open_cached() without having to worry about conflicting
CLOSE calls (this is only true for NFSv4.0 - NFSv4.1 can resolve
conflicts using nfs41_test_and_free_expired_stateid()).
Yes, agree.
Thanks a lot for the detail explain, but with latter kernel diff and
testcase(sleep in kernel will help increase the recurrence probability),
use-after-free can still happen.
# kernel diff:
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index c2045a2a9d0f..1502f39ee18c 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -250,6 +250,7 @@ struct nfs4_opendata {
bool is_recover;
bool cancelled;
int rpc_status;
+ struct rpc_task *task;
};
struct nfs4_add_xprt_data {
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 4685621ba469..04fdc019965e 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2506,6 +2506,9 @@ static void nfs4_open_prepare(struct rpc_task
*task, void *calldata)
struct nfs_client *clp = sp->so_server->nfs_client;
enum open_claim_type4 claim = data->o_arg.claim;
+ if (!(data->task))
+ data->task = task;
+ printk("%s data %llx task %llx\n", __func__, data, task);
if (nfs_wait_on_sequence(data->o_arg.seqid, task) != 0)
goto out_wait;
/*
@@ -2603,7 +2606,10 @@ static void nfs4_open_release(void *calldata)
struct nfs4_opendata *data = calldata;
struct nfs4_state *state = NULL;
+ printk("%s data %llx task %llx cancelled %d rpc_status %d
rpc_done %d tk_status %d\n",
+ __func__, data, data->task, data->cancelled,
data->rpc_status, data->rpc_done, data->task->tk_status);
+ if (data->rpc_status != 0 && !data->rpc_done)
+ nfs_release_seqid(data->o_arg.seqid);
/* If this request hasn't been cancelled, do nothing */
if (!data->cancelled)
goto out_free;
@@ -2669,12 +2675,14 @@ static int nfs4_run_open_task(struct
nfs4_opendata *data,
task = rpc_run_task(&task_setup_data);
if (IS_ERR(task))
return PTR_ERR(task);
+ msleep(100);
status = rpc_wait_for_completion_task(task);
if (status != 0) {
data->cancelled = true;
smp_wmb();
} else
status = data->rpc_status;
+ msleep(100);
rpc_put_task(task);
return status;
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 877f682b45f2..81d31b7f723f 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1100,6 +1100,7 @@ void nfs_release_seqid(struct nfs_seqid *seqid)
next = list_first_entry(&sequence->list,
struct nfs_seqid, list);
+ mdelay(100);
rpc_wake_up_queued_task(&sequence->wait, next->task);
}
spin_unlock(&sequence->lock);
# testcase:
#!/bin/bash
mkdir /mnt/sda
mkdir /mnt/sdb
mkdir /mnt1
touch /mnt/sda/file
touch /mnt/sdb/file
echo "/ *(rw,no_root_squash,fsid=0)" > /etc/exports
echo "/mnt *(rw,no_root_squash,fsid=1)" >> /etc/exports
exportfs -ra
service nfs-server start
while true; do umount -f /mnt1; done &
while true; do
echo "will mount"
mount -t nfs -o vers=4.0 127.0.0.1:/mnt /mnt1
exec 4<> /mnt1/sda/file &
exec 5<> /mnt1/sdb/file &
wait
umount /mnt1
echo "umount ok"
done
[ 94.159337] nfs4_open_prepare data ff11000006eec800 task ff110000472e9040
[ 94.172653] nfs4_open_prepare data ff11000006eed800 task ff110000472e88c0
[ 94.369424] nfs4_open_release data ff11000006eec800 task
ff110000472e9040 cancelled 0 rpc_status -10013 rpc_done 1 tk_status -10013
[ 94.417483] nfs4_open_release data ff11000006eed800 task
ff110000472e88c0 cancelled 0 rpc_status -512 rpc_done 1 tk_status -512
[ 94.476518]
==================================================================
[ 94.477340] BUG: KASAN: slab-use-after-free in
rpc_wake_up_queued_task+0x2c/0xc0
[ 94.478850] Read of size 8 at addr ff110000472e88f0 by task sh/856
[ 94.479553]
[ 94.479818] CPU: 2 UID: 0 PID: 856 Comm: sh Not tainted
6.11.0-09961-g2db5fff64932-dirty #23
[ 94.481326] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.16.1-2.fc37 04/01/2014
[ 94.483107] Call Trace:
[ 94.483683] <TASK>
[ 94.483924] dump_stack_lvl+0xa3/0x120
[ 94.484874] print_address_description.constprop.0+0x63/0x510
[ 94.486651] print_report+0xf5/0x360
[ 94.490550] kasan_report+0xd9/0x140
[ 94.491764] kasan_check_range+0x2d1/0x300
[ 94.492365] __kasan_check_read+0x21/0x30
[ 94.492817] rpc_wake_up_queued_task+0x2c/0xc0
[ 94.493377] nfs_release_seqid+0x1f8/0x300
[ 94.493935] nfs_free_seqid+0x1a/0x40
[ 94.494421] nfs4_opendata_free+0xc6/0x3e0
[ 94.495078] _nfs4_do_open+0xc0a/0x13b0
[ 94.504619] nfs4_do_open+0x26d/0x5e0
[ 94.507678] nfs4_atomic_open+0x2c6/0x3a0
[ 94.509928] nfs_atomic_open+0x4f8/0x1180
[ 94.514713] atomic_open+0x186/0x4e0
[ 94.515142] lookup_open.isra.0+0x3e7/0x15b0
[ 94.516519] open_last_lookups+0x85d/0x1260
[ 94.517032] path_openat+0x151/0x7b0
[ 94.518016] do_filp_open+0x1e0/0x310
[ 94.521059] do_sys_openat2+0x178/0x1f0
[ 94.524375] do_sys_open+0xa2/0x100
[ 94.526394] __x64_sys_openat+0xa8/0x120
[ 94.526857] x64_sys_call+0x2507/0x4540
[ 94.527289] do_syscall_64+0xa7/0x240
[ 94.527760] entry_SYSCALL_64_after_hwframe+0x76/0x7e
...
[ 94.536712]
[ 94.536896] Allocated by task 857:
[ 94.537321] kasan_save_stack+0x3b/0x70
[ 94.537810] kasan_save_track+0x1c/0x40
[ 94.538330] kasan_save_alloc_info+0x44/0x70
[ 94.538829] __kasan_slab_alloc+0xaf/0xc0
[ 94.539298] kmem_cache_alloc_noprof+0x1e0/0x4f0
[ 94.539903] rpc_new_task+0xe7/0x220
[ 94.540321] rpc_run_task+0x27/0x7d0
[ 94.540836] nfs4_run_open_task+0x477/0x810
[ 94.541380] _nfs4_proc_open+0xc0/0x6d0
[ 94.541905] _nfs4_open_and_get_state+0x178/0xc50
[ 94.542476] _nfs4_do_open+0x4a6/0x13b0
[ 94.542967] nfs4_do_open+0x26d/0x5e0
[ 94.543473] nfs4_atomic_open+0x2c6/0x3a0
[ 94.543947] nfs_atomic_open+0x4f8/0x1180
[ 94.544398] atomic_open+0x186/0x4e0
[ 94.544862] lookup_open.isra.0+0x3e7/0x15b0
[ 94.545406] open_last_lookups+0x85d/0x1260
[ 94.545878] path_openat+0x151/0x7b0
[ 94.546387] do_filp_open+0x1e0/0x310
[ 94.546868] do_sys_openat2+0x178/0x1f0
[ 94.547341] do_sys_open+0xa2/0x100
[ 94.547799] __x64_sys_openat+0xa8/0x120
[ 94.548335] x64_sys_call+0x2507/0x4540
[ 94.548819] do_syscall_64+0xa7/0x240
[ 94.549317] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 94.549969]
[ 94.550177] Freed by task 857:
[ 94.550603] kasan_save_stack+0x3b/0x70
[ 94.551101] kasan_save_track+0x1c/0x40
[ 94.551558] kasan_save_free_info+0x43/0x80
[ 94.552140] __kasan_slab_free+0x4f/0x90
[ 94.552587] kmem_cache_free+0x199/0x4f0
[ 94.553111] mempool_free_slab+0x1f/0x30
[ 94.553600] mempool_free+0xdf/0x3d0
[ 94.554072] rpc_free_task+0x12d/0x180
[ 94.554525] rpc_final_put_task+0x10e/0x150
[ 94.555022] rpc_do_put_task+0x63/0x80
[ 94.555532] rpc_put_task+0x18/0x30
[ 94.556004] nfs4_run_open_task+0x506/0x810
[ 94.556491] _nfs4_proc_open+0xc0/0x6d0
[ 94.557008] _nfs4_open_and_get_state+0x178/0xc50
[ 94.557551] _nfs4_do_open+0x4a6/0x13b0
[ 94.557982] nfs4_do_open+0x26d/0x5e0
[ 94.558464] nfs4_atomic_open+0x2c6/0x3a0
[ 94.558968] nfs_atomic_open+0x4f8/0x1180
[ 94.559428] atomic_open+0x186/0x4e0
[ 94.559818] lookup_open.isra.0+0x3e7/0x15b0
[ 94.560327] open_last_lookups+0x85d/0x1260
[ 94.560831] path_openat+0x151/0x7b0
[ 94.561330] do_filp_open+0x1e0/0x310
[ 94.561770] do_sys_openat2+0x178/0x1f0
[ 94.562184] do_sys_open+0xa2/0x100
[ 94.562563] __x64_sys_openat+0xa8/0x120
[ 94.563057] x64_sys_call+0x2507/0x4540
[ 94.563532] do_syscall_64+0xa7/0x240
[ 94.563956] entry_SYSCALL_64_after_hwframe+0x76/0x7e
Things go like this:
Thread A Thread B
// _nfs4_do_open
opendata1 and seqid1
// nfs4_run_open_task
rpc_task1
// _nfs4_do_open
opendata2 and seqid2
// nfs4_run_open_task
rpc_task2
// nfs4_run_open_task
rpc_task1 free
-------------------------------------------------------
umount -f generate signal
-------------------------------------------------------
// wakeup by signal
rpc_task2 free, seqid2 still
alive since rpc_status == -512,
rpc_done == true
// _nfs4_do_open
put opendata1 and
then nfs_free_seqid
release seqid1, wakeup
rpc_task2, but task2 has
been freed, UAF!!!!!!
// _nfs4_do_open
put opendata2 and release seqid2,
but it's too later...
Actually, once seqid2 can be released correctly, use-after-free may also
trigger...
Thread A Thread B
// _nfs4_do_open
opendata1 and seqid1
// nfs4_run_open_task
rpc_task1
// _nfs4_do_open
opendata2 and seqid2
// nfs4_run_open_task
rpc_task2
// nfs4_run_open_task
rpc_task1 free
-------------------------------------------------------
umount -f generate signal
-------------------------------------------------------
// wakeup by signal
rpc_task2 free, and nfs_free_seqid
will be trigger, try to wakeup
rpc_task1, trigger UAF!!!!
// _nfs4_do_open
put opendata1 and
then nfs_free_seqid
release seqid1, but
too later...
// _nfs4_do_open
put opendata2 and release seqid2
How about ping task->tk_count, and not release it until nfs_release_seqid...
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 877f682b45f2..15eb6ef611fb 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1095,11 +1095,14 @@ void nfs_release_seqid(struct nfs_seqid *seqid)
sequence = seqid->sequence;
spin_lock(&sequence->lock);
list_del_init(&seqid->list);
+ if (seqid->task)
+ rpc_put_task(seqid->task);
if (!list_empty(&sequence->list)) {
struct nfs_seqid *next;
next = list_first_entry(&sequence->list,
struct nfs_seqid, list);
+ mdelay(100);
rpc_wake_up_queued_task(&sequence->wait, next->task);
}
spin_unlock(&sequence->lock);
@@ -1181,8 +1184,10 @@ int nfs_wait_on_sequence(struct nfs_seqid *seqid,
struct rpc_task *task)
sequence = seqid->sequence;
spin_lock(&sequence->lock);
seqid->task = task;
- if (list_empty(&seqid->list))
+ if (list_empty(&seqid->list)) {
list_add_tail(&seqid->list, &sequence->list);
+ atomic_inc(&task->tk_count);
+ }
if (list_first_entry(&sequence->list, struct nfs_seqid, list)
== seqid)
goto unlock;
rpc_sleep_on(&sequence->wait, task, NULL);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b8ffbe52ba15..d2d7d84f0ed2 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2603,6 +2603,8 @@ static void nfs4_open_release(void *calldata)
struct nfs4_opendata *data = calldata;
struct nfs4_state *state = NULL;
+ if (data->cancelled || data->rpc_status != 0 || !data-
rpc_done)
+ nfs_release_seqid(data->o_arg.seqid);
/* If this request hasn't been cancelled, do nothing */
if (!data->cancelled)
goto out_free;
Looking forward to your reply!
See inlined comments above. Thanks!
