* [PATCH] KEYS: Fix an RCU warning
@ 2010-04-20 10:25 David Howells
2010-04-20 12:46 ` Eric Dumazet
0 siblings, 1 reply; 5+ messages in thread
From: David Howells @ 2010-04-20 10:25 UTC (permalink / raw)
To: torvalds, akpm, eric.dumazet; +Cc: dhowells, keyrings, linux-kernel
Fix the following RCU warning:
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
security/keys/request_key.c:116 invoked rcu_dereference_check() without protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 0
1 lock held by keyctl/5372:
#0: (key_types_sem){.+.+.+}, at: [<ffffffff811a4e3d>] key_type_lookup+0x1c/0x70
stack backtrace:
Pid: 5372, comm: keyctl Not tainted 2.6.34-rc3-cachefs #150
Call Trace:
[<ffffffff810515f8>] lockdep_rcu_dereference+0xaa/0xb2
[<ffffffff811a9220>] call_sbin_request_key+0x156/0x2b6
[<ffffffff811a4c66>] ? __key_instantiate_and_link+0xb1/0xdc
[<ffffffff811a4cd3>] ? key_instantiate_and_link+0x42/0x5f
[<ffffffff811a96b8>] ? request_key_auth_new+0x17b/0x1f3
[<ffffffff811a8e00>] ? request_key_and_link+0x271/0x400
[<ffffffff810aba6f>] ? kmem_cache_alloc+0xe1/0x118
[<ffffffff811a8f1a>] request_key_and_link+0x38b/0x400
[<ffffffff811a7b72>] sys_request_key+0xf7/0x14a
[<ffffffff81052227>] ? trace_hardirqs_on_caller+0x10c/0x130
[<ffffffff81393f5c>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b
This was caused by doing:
[root@andromeda ~]# keyctl newring fred @s
539196288
[root@andromeda ~]# keyctl request2 user a a 539196288
request_key: Required key not available
Signed-off-by: David Howells <dhowells@redhat.com>
---
security/keys/request_key.c | 13 ++++++++-----
1 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 03fe63e..ea97c31 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -68,7 +68,8 @@ static int call_sbin_request_key(struct key_construction *cons,
{
const struct cred *cred = current_cred();
key_serial_t prkey, sskey;
- struct key *key = cons->key, *authkey = cons->authkey, *keyring;
+ struct key *key = cons->key, *authkey = cons->authkey, *keyring,
+ *session;
char *argv[9], *envp[3], uid_str[12], gid_str[12];
char key_str[12], keyring_str[3][12];
char desc[20];
@@ -112,10 +113,12 @@ static int call_sbin_request_key(struct key_construction *cons,
if (cred->tgcred->process_keyring)
prkey = cred->tgcred->process_keyring->serial;
- if (cred->tgcred->session_keyring)
- sskey = rcu_dereference(cred->tgcred->session_keyring)->serial;
- else
- sskey = cred->user->session_keyring->serial;
+ rcu_read_lock();
+ session = rcu_dereference(cred->tgcred->session_keyring);
+ if (!session)
+ session = cred->user->session_keyring;
+ sskey = session->serial;
+ rcu_read_unlock();
sprintf(keyring_str[2], "%d", sskey);
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] KEYS: Fix an RCU warning
2010-04-20 10:25 [PATCH] KEYS: Fix an RCU warning David Howells
@ 2010-04-20 12:46 ` Eric Dumazet
2010-04-21 20:11 ` Paul E. McKenney
0 siblings, 1 reply; 5+ messages in thread
From: Eric Dumazet @ 2010-04-20 12:46 UTC (permalink / raw)
To: David Howells; +Cc: torvalds, akpm, keyrings, linux-kernel
Le mardi 20 avril 2010 à 11:25 +0100, David Howells a écrit :
> Fix the following RCU warning:
>
> ===================================================
> [ INFO: suspicious rcu_dereference_check() usage. ]
> ---------------------------------------------------
> security/keys/request_key.c:116 invoked rcu_dereference_check() without protection!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 1, debug_locks = 0
> 1 lock held by keyctl/5372:
> #0: (key_types_sem){.+.+.+}, at: [<ffffffff811a4e3d>] key_type_lookup+0x1c/0x70
>
> stack backtrace:
> Pid: 5372, comm: keyctl Not tainted 2.6.34-rc3-cachefs #150
> Call Trace:
> [<ffffffff810515f8>] lockdep_rcu_dereference+0xaa/0xb2
> [<ffffffff811a9220>] call_sbin_request_key+0x156/0x2b6
> [<ffffffff811a4c66>] ? __key_instantiate_and_link+0xb1/0xdc
> [<ffffffff811a4cd3>] ? key_instantiate_and_link+0x42/0x5f
> [<ffffffff811a96b8>] ? request_key_auth_new+0x17b/0x1f3
> [<ffffffff811a8e00>] ? request_key_and_link+0x271/0x400
> [<ffffffff810aba6f>] ? kmem_cache_alloc+0xe1/0x118
> [<ffffffff811a8f1a>] request_key_and_link+0x38b/0x400
> [<ffffffff811a7b72>] sys_request_key+0xf7/0x14a
> [<ffffffff81052227>] ? trace_hardirqs_on_caller+0x10c/0x130
> [<ffffffff81393f5c>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> [<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b
>
> This was caused by doing:
>
> [root@andromeda ~]# keyctl newring fred @s
> 539196288
> [root@andromeda ~]# keyctl request2 user a a 539196288
> request_key: Required key not available
>
> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Thanks !
> security/keys/request_key.c | 13 ++++++++-----
> 1 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/security/keys/request_key.c b/security/keys/request_key.c
> index 03fe63e..ea97c31 100644
> --- a/security/keys/request_key.c
> +++ b/security/keys/request_key.c
> @@ -68,7 +68,8 @@ static int call_sbin_request_key(struct key_construction *cons,
> {
> const struct cred *cred = current_cred();
> key_serial_t prkey, sskey;
> - struct key *key = cons->key, *authkey = cons->authkey, *keyring;
> + struct key *key = cons->key, *authkey = cons->authkey, *keyring,
> + *session;
> char *argv[9], *envp[3], uid_str[12], gid_str[12];
> char key_str[12], keyring_str[3][12];
> char desc[20];
> @@ -112,10 +113,12 @@ static int call_sbin_request_key(struct key_construction *cons,
> if (cred->tgcred->process_keyring)
> prkey = cred->tgcred->process_keyring->serial;
>
> - if (cred->tgcred->session_keyring)
> - sskey = rcu_dereference(cred->tgcred->session_keyring)->serial;
> - else
> - sskey = cred->user->session_keyring->serial;
> + rcu_read_lock();
> + session = rcu_dereference(cred->tgcred->session_keyring);
> + if (!session)
> + session = cred->user->session_keyring;
> + sskey = session->serial;
> + rcu_read_unlock();
>
> sprintf(keyring_str[2], "%d", sskey);
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] KEYS: Fix an RCU warning
2010-04-20 12:46 ` Eric Dumazet
@ 2010-04-21 20:11 ` Paul E. McKenney
0 siblings, 0 replies; 5+ messages in thread
From: Paul E. McKenney @ 2010-04-21 20:11 UTC (permalink / raw)
To: Eric Dumazet; +Cc: David Howells, torvalds, akpm, keyrings, linux-kernel
On Tue, Apr 20, 2010 at 02:46:04PM +0200, Eric Dumazet wrote:
> Le mardi 20 avril 2010 à 11:25 +0100, David Howells a écrit :
> > Fix the following RCU warning:
> >
> > ===================================================
> > [ INFO: suspicious rcu_dereference_check() usage. ]
> > ---------------------------------------------------
> > security/keys/request_key.c:116 invoked rcu_dereference_check() without protection!
> >
> > other info that might help us debug this:
> >
> >
> > rcu_scheduler_active = 1, debug_locks = 0
> > 1 lock held by keyctl/5372:
> > #0: (key_types_sem){.+.+.+}, at: [<ffffffff811a4e3d>] key_type_lookup+0x1c/0x70
> >
> > stack backtrace:
> > Pid: 5372, comm: keyctl Not tainted 2.6.34-rc3-cachefs #150
> > Call Trace:
> > [<ffffffff810515f8>] lockdep_rcu_dereference+0xaa/0xb2
> > [<ffffffff811a9220>] call_sbin_request_key+0x156/0x2b6
> > [<ffffffff811a4c66>] ? __key_instantiate_and_link+0xb1/0xdc
> > [<ffffffff811a4cd3>] ? key_instantiate_and_link+0x42/0x5f
> > [<ffffffff811a96b8>] ? request_key_auth_new+0x17b/0x1f3
> > [<ffffffff811a8e00>] ? request_key_and_link+0x271/0x400
> > [<ffffffff810aba6f>] ? kmem_cache_alloc+0xe1/0x118
> > [<ffffffff811a8f1a>] request_key_and_link+0x38b/0x400
> > [<ffffffff811a7b72>] sys_request_key+0xf7/0x14a
> > [<ffffffff81052227>] ? trace_hardirqs_on_caller+0x10c/0x130
> > [<ffffffff81393f5c>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> > [<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b
> >
> > This was caused by doing:
> >
> > [root@andromeda ~]# keyctl newring fred @s
> > 539196288
> > [root@andromeda ~]# keyctl request2 user a a 539196288
> > request_key: Required key not available
> >
> > Signed-off-by: David Howells <dhowells@redhat.com>
> > ---
> >
>
> Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
>
> Thanks !
Queued for 2.6.34, thank you both!
Thanx, Paul
> > security/keys/request_key.c | 13 ++++++++-----
> > 1 files changed, 8 insertions(+), 5 deletions(-)
> >
> > diff --git a/security/keys/request_key.c b/security/keys/request_key.c
> > index 03fe63e..ea97c31 100644
> > --- a/security/keys/request_key.c
> > +++ b/security/keys/request_key.c
> > @@ -68,7 +68,8 @@ static int call_sbin_request_key(struct key_construction *cons,
> > {
> > const struct cred *cred = current_cred();
> > key_serial_t prkey, sskey;
> > - struct key *key = cons->key, *authkey = cons->authkey, *keyring;
> > + struct key *key = cons->key, *authkey = cons->authkey, *keyring,
> > + *session;
> > char *argv[9], *envp[3], uid_str[12], gid_str[12];
> > char key_str[12], keyring_str[3][12];
> > char desc[20];
> > @@ -112,10 +113,12 @@ static int call_sbin_request_key(struct key_construction *cons,
> > if (cred->tgcred->process_keyring)
> > prkey = cred->tgcred->process_keyring->serial;
> >
> > - if (cred->tgcred->session_keyring)
> > - sskey = rcu_dereference(cred->tgcred->session_keyring)->serial;
> > - else
> > - sskey = cred->user->session_keyring->serial;
> > + rcu_read_lock();
> > + session = rcu_dereference(cred->tgcred->session_keyring);
> > + if (!session)
> > + session = cred->user->session_keyring;
> > + sskey = session->serial;
> > + rcu_read_unlock();
> >
> > sprintf(keyring_str[2], "%d", sskey);
> >
> >
>
>
> --
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^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] KEYS: Fix an RCU warning
@ 2010-04-07 14:14 David Howells
2010-04-07 14:49 ` Eric Dumazet
0 siblings, 1 reply; 5+ messages in thread
From: David Howells @ 2010-04-07 14:14 UTC (permalink / raw)
To: torvalds, akpm; +Cc: keyrings, linux-kernel, David Howells
Fix the following RCU warning:
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
security/keys/request_key.c:116 invoked rcu_dereference_check() without protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 0
1 lock held by keyctl/5372:
#0: (key_types_sem){.+.+.+}, at: [<ffffffff811a4e3d>] key_type_lookup+0x1c/0x70
stack backtrace:
Pid: 5372, comm: keyctl Not tainted 2.6.34-rc3-cachefs #150
Call Trace:
[<ffffffff810515f8>] lockdep_rcu_dereference+0xaa/0xb2
[<ffffffff811a9220>] call_sbin_request_key+0x156/0x2b6
[<ffffffff811a4c66>] ? __key_instantiate_and_link+0xb1/0xdc
[<ffffffff811a4cd3>] ? key_instantiate_and_link+0x42/0x5f
[<ffffffff811a96b8>] ? request_key_auth_new+0x17b/0x1f3
[<ffffffff811a8e00>] ? request_key_and_link+0x271/0x400
[<ffffffff810aba6f>] ? kmem_cache_alloc+0xe1/0x118
[<ffffffff811a8f1a>] request_key_and_link+0x38b/0x400
[<ffffffff811a7b72>] sys_request_key+0xf7/0x14a
[<ffffffff81052227>] ? trace_hardirqs_on_caller+0x10c/0x130
[<ffffffff81393f5c>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b
This was caused by doing:
[root@andromeda ~]# keyctl newring fred @s
539196288
[root@andromeda ~]# keyctl request2 user a a 539196288
request_key: Required key not available
Signed-off-by: David Howells <dhowells@redhat.com>
---
security/keys/request_key.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 03fe63e..544e932 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -112,10 +112,13 @@ static int call_sbin_request_key(struct key_construction *cons,
if (cred->tgcred->process_keyring)
prkey = cred->tgcred->process_keyring->serial;
- if (cred->tgcred->session_keyring)
+ if (cred->tgcred->session_keyring) {
+ rcu_read_lock();
sskey = rcu_dereference(cred->tgcred->session_keyring)->serial;
- else
+ rcu_read_unlock();
+ } else {
sskey = cred->user->session_keyring->serial;
+ }
sprintf(keyring_str[2], "%d", sskey);
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] KEYS: Fix an RCU warning
2010-04-07 14:14 David Howells
@ 2010-04-07 14:49 ` Eric Dumazet
0 siblings, 0 replies; 5+ messages in thread
From: Eric Dumazet @ 2010-04-07 14:49 UTC (permalink / raw)
To: David Howells; +Cc: torvalds, akpm, keyrings, linux-kernel
Le mercredi 07 avril 2010 à 15:14 +0100, David Howells a écrit :
> Fix the following RCU warning:
>
> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
>
> security/keys/request_key.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/security/keys/request_key.c b/security/keys/request_key.c
> index 03fe63e..544e932 100644
> --- a/security/keys/request_key.c
> +++ b/security/keys/request_key.c
> @@ -112,10 +112,13 @@ static int call_sbin_request_key(struct key_construction *cons,
> if (cred->tgcred->process_keyring)
> prkey = cred->tgcred->process_keyring->serial;
>
> - if (cred->tgcred->session_keyring)
> + if (cred->tgcred->session_keyring) {
> + rcu_read_lock();
> sskey = rcu_dereference(cred->tgcred->session_keyring)->serial;
> - else
> + rcu_read_unlock();
> + } else {
> sskey = cred->user->session_keyring->serial;
> + }
>
> sprintf(keyring_str[2], "%d", sskey);
>
This fix is really wrong David.
You should instead do :
rcu_read_lock();
skeyring = rcu_dereference(cred->tgcred->session_keyring);
if (skeyring)
sskey = sskeyring->serial;
else
sskey = cred->user->session_keyring->serial;
rcu_read_unlock();
^ permalink raw reply [flat|nested] 5+ messages in thread
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2010-04-20 10:25 [PATCH] KEYS: Fix an RCU warning David Howells
2010-04-20 12:46 ` Eric Dumazet
2010-04-21 20:11 ` Paul E. McKenney
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2010-04-07 14:14 David Howells
2010-04-07 14:49 ` Eric Dumazet
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