* FAILED: patch "[PATCH] nfsd: fix use-after-free due to delegation race" failed to apply to 4.19-stable tree
@ 2021-12-12 13:11 gregkh
2021-12-16 20:05 ` Salvatore Bonaccorso
0 siblings, 1 reply; 4+ messages in thread
From: gregkh @ 2021-12-12 13:11 UTC (permalink / raw)
To: bfields; +Cc: stable
The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 548ec0805c399c65ed66c6641be467f717833ab5 Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Mon, 29 Nov 2021 15:08:00 -0500
Subject: [PATCH] nfsd: fix use-after-free due to delegation race
A delegation break could arrive as soon as we've called vfs_setlease. A
delegation break runs a callback which immediately (in
nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we
then exit nfs4_set_delegation without hashing the delegation, it will be
freed as soon as the callback is done with it, without ever being
removed from del_recall_lru.
Symptoms show up later as use-after-free or list corruption warnings,
usually in the laundromat thread.
I suspect aba2072f4523 "nfsd: grant read delegations to clients holding
writes" made this bug easier to hit, but I looked as far back as v3.0
and it looks to me it already had the same problem. So I'm not sure
where the bug was introduced; it may have been there from the beginning.
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index bfad94c70b84..1956d377d1a6 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1207,6 +1207,11 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp)
return 0;
}
+static bool delegation_hashed(struct nfs4_delegation *dp)
+{
+ return !(list_empty(&dp->dl_perfile));
+}
+
static bool
unhash_delegation_locked(struct nfs4_delegation *dp)
{
@@ -1214,7 +1219,7 @@ unhash_delegation_locked(struct nfs4_delegation *dp)
lockdep_assert_held(&state_lock);
- if (list_empty(&dp->dl_perfile))
+ if (!delegation_hashed(dp))
return false;
dp->dl_stid.sc_type = NFS4_CLOSED_DELEG_STID;
@@ -4598,7 +4603,7 @@ static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb)
* queued for a lease break. Don't queue it again.
*/
spin_lock(&state_lock);
- if (dp->dl_time == 0) {
+ if (delegation_hashed(dp) && dp->dl_time == 0) {
dp->dl_time = ktime_get_boottime_seconds();
list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
}
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: FAILED: patch "[PATCH] nfsd: fix use-after-free due to delegation race" failed to apply to 4.19-stable tree
2021-12-12 13:11 FAILED: patch "[PATCH] nfsd: fix use-after-free due to delegation race" failed to apply to 4.19-stable tree gregkh
@ 2021-12-16 20:05 ` Salvatore Bonaccorso
2021-12-17 2:42 ` Bruce Fields
0 siblings, 1 reply; 4+ messages in thread
From: Salvatore Bonaccorso @ 2021-12-16 20:05 UTC (permalink / raw)
To: gregkh; +Cc: bfields, stable
Hi Bruce, hi Greg,
On Sun, Dec 12, 2021 at 02:11:30PM +0100, gregkh@linuxfoundation.org wrote:
>
> The patch below does not apply to the 4.19-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
Unless I'm completely wrong this only does not apply to the older
series because in 5.6-rc1 we had 20b7d86f29d3 ("nfsd: use boottime for
lease expiry calculation") soe there is a minor context change in one
hunk.
Attached is a patch accounting for that, Bruce is this okay?
This would apply as well back on top of v4.9.293.
Regards,
Salvatore
From eeeaf376a2efabdad46ce03516552f4290949834 Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Mon, 29 Nov 2021 15:08:00 -0500
Subject: [PATCH] nfsd: fix use-after-free due to delegation race
commit 548ec0805c399c65ed66c6641be467f717833ab5 upstream.
A delegation break could arrive as soon as we've called vfs_setlease. A
delegation break runs a callback which immediately (in
nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we
then exit nfs4_set_delegation without hashing the delegation, it will be
freed as soon as the callback is done with it, without ever being
removed from del_recall_lru.
Symptoms show up later as use-after-free or list corruption warnings,
usually in the laundromat thread.
I suspect aba2072f4523 "nfsd: grant read delegations to clients holding
writes" made this bug easier to hit, but I looked as far back as v3.0
and it looks to me it already had the same problem. So I'm not sure
where the bug was introduced; it may have been there from the beginning.
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[Salvatore Bonaccorso: Backport for context changes to versions which do
not have 20b7d86f29d3 ("nfsd: use boottime for lease expiry
calculation")]
Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
---
fs/nfsd/nfs4state.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 655079ae1dd1..dfb2a790efc1 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -975,6 +975,11 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp)
return 0;
}
+static bool delegation_hashed(struct nfs4_delegation *dp)
+{
+ return !(list_empty(&dp->dl_perfile));
+}
+
static bool
unhash_delegation_locked(struct nfs4_delegation *dp)
{
@@ -982,7 +987,7 @@ unhash_delegation_locked(struct nfs4_delegation *dp)
lockdep_assert_held(&state_lock);
- if (list_empty(&dp->dl_perfile))
+ if (!delegation_hashed(dp))
return false;
dp->dl_stid.sc_type = NFS4_CLOSED_DELEG_STID;
@@ -3912,7 +3917,7 @@ static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb)
* queued for a lease break. Don't queue it again.
*/
spin_lock(&state_lock);
- if (dp->dl_time == 0) {
+ if (delegation_hashed(dp) && dp->dl_time == 0) {
dp->dl_time = get_seconds();
list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
}
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: FAILED: patch "[PATCH] nfsd: fix use-after-free due to delegation race" failed to apply to 4.19-stable tree
2021-12-16 20:05 ` Salvatore Bonaccorso
@ 2021-12-17 2:42 ` Bruce Fields
2021-12-17 13:52 ` Greg KH
0 siblings, 1 reply; 4+ messages in thread
From: Bruce Fields @ 2021-12-17 2:42 UTC (permalink / raw)
To: Salvatore Bonaccorso; +Cc: gregkh, stable
On Thu, Dec 16, 2021 at 3:05 PM Salvatore Bonaccorso <carnil@debian.org> wrote:
> On Sun, Dec 12, 2021 at 02:11:30PM +0100, gregkh@linuxfoundation.org wrote:
> > The patch below does not apply to the 4.19-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
>
> Unless I'm completely wrong this only does not apply to the older
> series because in 5.6-rc1 we had 20b7d86f29d3 ("nfsd: use boottime for
> lease expiry calculation") soe there is a minor context change in one
> hunk.
>
> Attached is a patch accounting for that, Bruce is this okay?
Yes, this looks fine to me. Thank you!
--b.
> This would apply as well back on top of v4.9.293.
>
> Regards,
> Salvatore
>
> From eeeaf376a2efabdad46ce03516552f4290949834 Mon Sep 17 00:00:00 2001
> From: "J. Bruce Fields" <bfields@redhat.com>
> Date: Mon, 29 Nov 2021 15:08:00 -0500
> Subject: [PATCH] nfsd: fix use-after-free due to delegation race
>
> commit 548ec0805c399c65ed66c6641be467f717833ab5 upstream.
>
> A delegation break could arrive as soon as we've called vfs_setlease. A
> delegation break runs a callback which immediately (in
> nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we
> then exit nfs4_set_delegation without hashing the delegation, it will be
> freed as soon as the callback is done with it, without ever being
> removed from del_recall_lru.
>
> Symptoms show up later as use-after-free or list corruption warnings,
> usually in the laundromat thread.
>
> I suspect aba2072f4523 "nfsd: grant read delegations to clients holding
> writes" made this bug easier to hit, but I looked as far back as v3.0
> and it looks to me it already had the same problem. So I'm not sure
> where the bug was introduced; it may have been there from the beginning.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> [Salvatore Bonaccorso: Backport for context changes to versions which do
> not have 20b7d86f29d3 ("nfsd: use boottime for lease expiry
> calculation")]
> Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
> ---
> fs/nfsd/nfs4state.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 655079ae1dd1..dfb2a790efc1 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -975,6 +975,11 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp)
> return 0;
> }
>
> +static bool delegation_hashed(struct nfs4_delegation *dp)
> +{
> + return !(list_empty(&dp->dl_perfile));
> +}
> +
> static bool
> unhash_delegation_locked(struct nfs4_delegation *dp)
> {
> @@ -982,7 +987,7 @@ unhash_delegation_locked(struct nfs4_delegation *dp)
>
> lockdep_assert_held(&state_lock);
>
> - if (list_empty(&dp->dl_perfile))
> + if (!delegation_hashed(dp))
> return false;
>
> dp->dl_stid.sc_type = NFS4_CLOSED_DELEG_STID;
> @@ -3912,7 +3917,7 @@ static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb)
> * queued for a lease break. Don't queue it again.
> */
> spin_lock(&state_lock);
> - if (dp->dl_time == 0) {
> + if (delegation_hashed(dp) && dp->dl_time == 0) {
> dp->dl_time = get_seconds();
> list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
> }
> --
> 2.34.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: FAILED: patch "[PATCH] nfsd: fix use-after-free due to delegation race" failed to apply to 4.19-stable tree
2021-12-17 2:42 ` Bruce Fields
@ 2021-12-17 13:52 ` Greg KH
0 siblings, 0 replies; 4+ messages in thread
From: Greg KH @ 2021-12-17 13:52 UTC (permalink / raw)
To: Bruce Fields; +Cc: Salvatore Bonaccorso, stable
On Thu, Dec 16, 2021 at 09:42:26PM -0500, Bruce Fields wrote:
> On Thu, Dec 16, 2021 at 3:05 PM Salvatore Bonaccorso <carnil@debian.org> wrote:
> > On Sun, Dec 12, 2021 at 02:11:30PM +0100, gregkh@linuxfoundation.org wrote:
> > > The patch below does not apply to the 4.19-stable tree.
> > > If someone wants it applied there, or to any other stable or longterm
> > > tree, then please email the backport, including the original git commit
> > > id to <stable@vger.kernel.org>.
> >
> > Unless I'm completely wrong this only does not apply to the older
> > series because in 5.6-rc1 we had 20b7d86f29d3 ("nfsd: use boottime for
> > lease expiry calculation") soe there is a minor context change in one
> > hunk.
> >
> > Attached is a patch accounting for that, Bruce is this okay?
>
> Yes, this looks fine to me. Thank you!
Now queued up, thanks.
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-12-17 13:52 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-12-12 13:11 FAILED: patch "[PATCH] nfsd: fix use-after-free due to delegation race" failed to apply to 4.19-stable tree gregkh
2021-12-16 20:05 ` Salvatore Bonaccorso
2021-12-17 2:42 ` Bruce Fields
2021-12-17 13:52 ` Greg KH
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