* [PATCH] neighbour: Prevent a dead entry from updating gc_list
@ 2021-01-27 16:54 Chinmay Agarwal
2021-01-28 2:34 ` Cong Wang
` (2 more replies)
0 siblings, 3 replies; 8+ messages in thread
From: Chinmay Agarwal @ 2021-01-27 16:54 UTC (permalink / raw)
To: xiyou.wangcong, Jakub Kicinski; +Cc: netdev, davem, sharathv
Following race condition was detected:
<CPU A, t0> - neigh_flush_dev() is under execution and calls
neigh_mark_dead(n) marking the neighbour entry 'n' as dead.
<CPU B, t1> - Executing: __netif_receive_skb() ->
__netif_receive_skb_core() -> arp_rcv() -> arp_process().arp_process()
calls __neigh_lookup() which takes a reference on neighbour entry 'n'.
<CPU A, t2> - Moves further along neigh_flush_dev() and calls
neigh_cleanup_and_release(n), but since reference count increased in t2,
'n' couldn't be destroyed.
<CPU B, t3> - Moves further along, arp_process() and calls
neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
the neighbour entry back in gc_list(neigh_mark_dead(), removed it
earlier in t0 from gc_list)
<CPU B, t4> - arp_process() finally calls neigh_release(n), destroying
the neighbour entry.
This leads to 'n' still being part of gc_list, but the actual
neighbour structure has been freed.
The situation can be prevented from happening if we disallow a dead
entry to have any possibility of updating gc_list. This is what the
patch intends to achieve.
Fixes: 9c29a2f55ec0 ("neighbor: Fix locking order for gc_list changes")
Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
---
net/core/neighbour.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index ff07358..e2982b3 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1244,13 +1244,14 @@ static int __neigh_update(struct neighbour *neigh, const u8 *lladdr,
old = neigh->nud_state;
err = -EPERM;
- if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
- (old & (NUD_NOARP | NUD_PERMANENT)))
- goto out;
if (neigh->dead) {
NL_SET_ERR_MSG(extack, "Neighbor entry is now dead");
+ new = old;
goto out;
}
+ if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
+ (old & (NUD_NOARP | NUD_PERMANENT)))
+ goto out;
ext_learn_change = neigh_update_ext_learned(neigh, flags, ¬ify);
--
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH] neighbour: Prevent a dead entry from updating gc_list
2021-01-27 16:54 [PATCH] neighbour: Prevent a dead entry from updating gc_list Chinmay Agarwal
@ 2021-01-28 2:34 ` Cong Wang
2021-01-30 16:05 ` David Ahern
2021-02-02 1:09 ` Jakub Kicinski
2 siblings, 0 replies; 8+ messages in thread
From: Cong Wang @ 2021-01-28 2:34 UTC (permalink / raw)
To: Chinmay Agarwal
Cc: Jakub Kicinski, Linux Kernel Network Developers, David Miller, sharathv
On Wed, Jan 27, 2021 at 8:55 AM Chinmay Agarwal <chinagar@codeaurora.org> wrote:
>
> Following race condition was detected:
> <CPU A, t0> - neigh_flush_dev() is under execution and calls
> neigh_mark_dead(n) marking the neighbour entry 'n' as dead.
>
> <CPU B, t1> - Executing: __netif_receive_skb() ->
> __netif_receive_skb_core() -> arp_rcv() -> arp_process().arp_process()
> calls __neigh_lookup() which takes a reference on neighbour entry 'n'.
>
> <CPU A, t2> - Moves further along neigh_flush_dev() and calls
> neigh_cleanup_and_release(n), but since reference count increased in t2,
> 'n' couldn't be destroyed.
>
> <CPU B, t3> - Moves further along, arp_process() and calls
> neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
> the neighbour entry back in gc_list(neigh_mark_dead(), removed it
> earlier in t0 from gc_list)
>
> <CPU B, t4> - arp_process() finally calls neigh_release(n), destroying
> the neighbour entry.
>
> This leads to 'n' still being part of gc_list, but the actual
> neighbour structure has been freed.
>
> The situation can be prevented from happening if we disallow a dead
> entry to have any possibility of updating gc_list. This is what the
> patch intends to achieve.
>
> Fixes: 9c29a2f55ec0 ("neighbor: Fix locking order for gc_list changes")
> Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Thanks.
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] neighbour: Prevent a dead entry from updating gc_list
2021-01-27 16:54 [PATCH] neighbour: Prevent a dead entry from updating gc_list Chinmay Agarwal
2021-01-28 2:34 ` Cong Wang
@ 2021-01-30 16:05 ` David Ahern
2021-02-02 1:09 ` Jakub Kicinski
2 siblings, 0 replies; 8+ messages in thread
From: David Ahern @ 2021-01-30 16:05 UTC (permalink / raw)
To: Chinmay Agarwal, xiyou.wangcong, Jakub Kicinski; +Cc: netdev, davem, sharathv
On 1/27/21 9:54 AM, Chinmay Agarwal wrote:
> Following race condition was detected:
> <CPU A, t0> - neigh_flush_dev() is under execution and calls
> neigh_mark_dead(n) marking the neighbour entry 'n' as dead.
>
> <CPU B, t1> - Executing: __netif_receive_skb() ->
> __netif_receive_skb_core() -> arp_rcv() -> arp_process().arp_process()
> calls __neigh_lookup() which takes a reference on neighbour entry 'n'.
>
> <CPU A, t2> - Moves further along neigh_flush_dev() and calls
> neigh_cleanup_and_release(n), but since reference count increased in t2,
> 'n' couldn't be destroyed.
>
> <CPU B, t3> - Moves further along, arp_process() and calls
> neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
> the neighbour entry back in gc_list(neigh_mark_dead(), removed it
> earlier in t0 from gc_list)
>
> <CPU B, t4> - arp_process() finally calls neigh_release(n), destroying
> the neighbour entry.
>
> This leads to 'n' still being part of gc_list, but the actual
> neighbour structure has been freed.
>
> The situation can be prevented from happening if we disallow a dead
> entry to have any possibility of updating gc_list. This is what the
> patch intends to achieve.
>
> Fixes: 9c29a2f55ec0 ("neighbor: Fix locking order for gc_list changes")
always Cc the author(s) of commits in Fixes tag.
> Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
> ---
> net/core/neighbour.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
Reviewed-by: David Ahern <dsahern@kernel.org>
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] neighbour: Prevent a dead entry from updating gc_list
2021-01-27 16:54 [PATCH] neighbour: Prevent a dead entry from updating gc_list Chinmay Agarwal
2021-01-28 2:34 ` Cong Wang
2021-01-30 16:05 ` David Ahern
@ 2021-02-02 1:09 ` Jakub Kicinski
2 siblings, 0 replies; 8+ messages in thread
From: Jakub Kicinski @ 2021-02-02 1:09 UTC (permalink / raw)
To: Chinmay Agarwal; +Cc: xiyou.wangcong, netdev, davem, sharathv
On Wed, 27 Jan 2021 22:24:54 +0530 Chinmay Agarwal wrote:
> Following race condition was detected:
> <CPU A, t0> - neigh_flush_dev() is under execution and calls
> neigh_mark_dead(n) marking the neighbour entry 'n' as dead.
>
> <CPU B, t1> - Executing: __netif_receive_skb() ->
> __netif_receive_skb_core() -> arp_rcv() -> arp_process().arp_process()
> calls __neigh_lookup() which takes a reference on neighbour entry 'n'.
>
> <CPU A, t2> - Moves further along neigh_flush_dev() and calls
> neigh_cleanup_and_release(n), but since reference count increased in t2,
> 'n' couldn't be destroyed.
>
> <CPU B, t3> - Moves further along, arp_process() and calls
> neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
> the neighbour entry back in gc_list(neigh_mark_dead(), removed it
> earlier in t0 from gc_list)
>
> <CPU B, t4> - arp_process() finally calls neigh_release(n), destroying
> the neighbour entry.
>
> This leads to 'n' still being part of gc_list, but the actual
> neighbour structure has been freed.
>
> The situation can be prevented from happening if we disallow a dead
> entry to have any possibility of updating gc_list. This is what the
> patch intends to achieve.
>
> Fixes: 9c29a2f55ec0 ("neighbor: Fix locking order for gc_list changes")
> Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
Applied, thanks!
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] neighbour: Prevent a dead entry from updating gc_list
@ 2021-01-25 19:59 Chinmay Agarwal
2021-01-25 21:07 ` Cong Wang
2021-01-25 21:59 ` Jakub Kicinski
0 siblings, 2 replies; 8+ messages in thread
From: Chinmay Agarwal @ 2021-01-25 19:59 UTC (permalink / raw)
To: netdev; +Cc: xiyou.wangcong, sharathv
Following race condition was detected:
<CPU A, t0> - neigh_flush_dev() is under execution and calls neigh_mark_dead(n),
marking the neighbour entry 'n' as dead.
<CPU B, t1> - Executing: __netif_receive_skb() -> __netif_receive_skb_core()
-> arp_rcv() -> arp_process().arp_process() calls __neigh_lookup() which takes
a reference on neighbour entry 'n'.
<CPU A, t2> - Moves further along neigh_flush_dev() and calls
neigh_cleanup_and_release(n), but since reference count increased in t2,
'n' couldn't be destroyed.
<CPU B, t3> - Moves further along, arp_process() and calls
neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
the neighbour entry back in gc_list(neigh_mark_dead(), removed it
earlier in t0 from gc_list)
<CPU B, t4> - arp_process() finally calls neigh_release(n), destroying
the neighbour entry.
This leads to 'n' still being part of gc_list, but the actual
neighbour structure has been freed.
The situation can be prevented from happening if we disallow a dead
entry to have any possibility of updating gc_list. This is what the
patch intends to achieve.
Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
---
net/core/neighbour.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index ff07358..cf8e3076 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1244,13 +1244,14 @@ static int __neigh_update(struct neighbour *neigh, const u8 *lladdr,
old = neigh->nud_state;
err = -EPERM;
- if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
- (old & (NUD_NOARP | NUD_PERMANENT)))
- goto out;
if (neigh->dead) {
NL_SET_ERR_MSG(extack, "Neighbor entry is now dead");
+ new=old;
goto out;
}
+ if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
+ (old & (NUD_NOARP | NUD_PERMANENT)))
+ goto out;
ext_learn_change = neigh_update_ext_learned(neigh, flags, ¬ify);
--
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH] neighbour: Prevent a dead entry from updating gc_list
2021-01-25 19:59 Chinmay Agarwal
@ 2021-01-25 21:07 ` Cong Wang
2021-01-25 21:59 ` Jakub Kicinski
1 sibling, 0 replies; 8+ messages in thread
From: Cong Wang @ 2021-01-25 21:07 UTC (permalink / raw)
To: Chinmay Agarwal; +Cc: Linux Kernel Network Developers, sharathv
On Mon, Jan 25, 2021 at 11:59 AM Chinmay Agarwal
<chinagar@codeaurora.org> wrote:
>
> Following race condition was detected:
> <CPU A, t0> - neigh_flush_dev() is under execution and calls neigh_mark_dead(n),
> marking the neighbour entry 'n' as dead.
>
> <CPU B, t1> - Executing: __netif_receive_skb() -> __netif_receive_skb_core()
> -> arp_rcv() -> arp_process().arp_process() calls __neigh_lookup() which takes
> a reference on neighbour entry 'n'.
>
> <CPU A, t2> - Moves further along neigh_flush_dev() and calls
> neigh_cleanup_and_release(n), but since reference count increased in t2,
> 'n' couldn't be destroyed.
>
> <CPU B, t3> - Moves further along, arp_process() and calls
> neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
> the neighbour entry back in gc_list(neigh_mark_dead(), removed it
> earlier in t0 from gc_list)
>
> <CPU B, t4> - arp_process() finally calls neigh_release(n), destroying
> the neighbour entry.
>
> This leads to 'n' still being part of gc_list, but the actual
> neighbour structure has been freed.
>
> The situation can be prevented from happening if we disallow a dead
> entry to have any possibility of updating gc_list. This is what the
> patch intends to achieve.
>
> Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
Please add a Fixes tag for bug fixes, in this case it is probably:
Fixes: 9c29a2f55ec0 ("neighbor: Fix locking order for gc_list changes")
And, make sure you run checkpatch.pl before sending out. For your
patch, it will definitely complain about the missing spaces around the
assignment "new=old;".
Thanks.
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] neighbour: Prevent a dead entry from updating gc_list
2021-01-25 19:59 Chinmay Agarwal
2021-01-25 21:07 ` Cong Wang
@ 2021-01-25 21:59 ` Jakub Kicinski
1 sibling, 0 replies; 8+ messages in thread
From: Jakub Kicinski @ 2021-01-25 21:59 UTC (permalink / raw)
To: Chinmay Agarwal; +Cc: netdev, xiyou.wangcong, sharathv
On Tue, 26 Jan 2021 01:29:37 +0530 Chinmay Agarwal wrote:
> Following race condition was detected:
> <CPU A, t0> - neigh_flush_dev() is under execution and calls neigh_mark_dead(n),
> marking the neighbour entry 'n' as dead.
>
> <CPU B, t1> - Executing: __netif_receive_skb() -> __netif_receive_skb_core()
> -> arp_rcv() -> arp_process().arp_process() calls __neigh_lookup() which takes
> a reference on neighbour entry 'n'.
>
> <CPU A, t2> - Moves further along neigh_flush_dev() and calls
> neigh_cleanup_and_release(n), but since reference count increased in t2,
> 'n' couldn't be destroyed.
>
> <CPU B, t3> - Moves further along, arp_process() and calls
> neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
> the neighbour entry back in gc_list(neigh_mark_dead(), removed it
> earlier in t0 from gc_list)
>
> <CPU B, t4> - arp_process() finally calls neigh_release(n), destroying
> the neighbour entry.
>
> This leads to 'n' still being part of gc_list, but the actual
> neighbour structure has been freed.
>
> The situation can be prevented from happening if we disallow a dead
> entry to have any possibility of updating gc_list. This is what the
> patch intends to achieve.
>
> Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
> ---
> net/core/neighbour.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index ff07358..cf8e3076 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -1244,13 +1244,14 @@ static int __neigh_update(struct neighbour *neigh, const u8 *lladdr,
> old = neigh->nud_state;
> err = -EPERM;
>
> - if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
> - (old & (NUD_NOARP | NUD_PERMANENT)))
> - goto out;
> if (neigh->dead) {
> NL_SET_ERR_MSG(extack, "Neighbor entry is now dead");
> + new=old;
> goto out;
> }
> + if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
> + (old & (NUD_NOARP | NUD_PERMANENT)))
> + goto out;
>
> ext_learn_change = neigh_update_ext_learned(neigh, flags, ¬ify);
>
Please run checkpatch on your patches:
ERROR: spaces required around that '=' (ctx:VxV)
#52: FILE: net/core/neighbour.c:1249:
+ new=old;
^
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] neighbour: Prevent a dead entry from updating gc_list
@ 2021-01-25 19:49 Chinmay Agarwal
0 siblings, 0 replies; 8+ messages in thread
From: Chinmay Agarwal @ 2021-01-25 19:49 UTC (permalink / raw)
To: netdev, davem, xiyou.wangcong; +Cc: sharathv
Following race condition was detected:
<CPU A, t0> - neigh_flush_dev() is under execution and calls neigh_mark_dead(n),
marking the neighbour entry 'n' as dead.
<CPU B, t1> - Executing: __netif_receive_skb() -> __netif_receive_skb_core()
-> arp_rcv() -> arp_process().arp_process() calls __neigh_lookup() which takes
a reference on neighbour entry 'n'.
<CPU A, t2> - Moves further along neigh_flush_dev() and calls
neigh_cleanup_and_release(n), but since reference count increased in t2,
'n' couldn't be destroyed.
<CPU B, t3> - Moves further along, arp_process() and calls
neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
the neighbour entry back in gc_list(neigh_mark_dead(), removed it
earlier in t0 from gc_list)
<CPU B, t4> - arp_process() finally calls neigh_release(n), destroying
the neighbour entry.
This leads to 'n' still being part of gc_list, but the actual
neighbour structure has been freed.
The situation can be prevented from happening if we disallow a dead
entry to have any possibility of updating gc_list. This is what the
patch intends to achieve.
Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
---
net/core/neighbour.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index ff07358..cf8e3076 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1244,13 +1244,14 @@ static int __neigh_update(struct neighbour *neigh, const u8 *lladdr,
old = neigh->nud_state;
err = -EPERM;
- if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
- (old & (NUD_NOARP | NUD_PERMANENT)))
- goto out;
if (neigh->dead) {
NL_SET_ERR_MSG(extack, "Neighbor entry is now dead");
+ new=old;
goto out;
}
+ if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
+ (old & (NUD_NOARP | NUD_PERMANENT)))
+ goto out;
ext_learn_change = neigh_update_ext_learned(neigh, flags, ¬ify);
--
^ permalink raw reply related [flat|nested] 8+ messages in thread
end of thread, other threads:[~2021-02-02 1:10 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-01-27 16:54 [PATCH] neighbour: Prevent a dead entry from updating gc_list Chinmay Agarwal
2021-01-28 2:34 ` Cong Wang
2021-01-30 16:05 ` David Ahern
2021-02-02 1:09 ` Jakub Kicinski
-- strict thread matches above, loose matches on Subject: below --
2021-01-25 19:59 Chinmay Agarwal
2021-01-25 21:07 ` Cong Wang
2021-01-25 21:59 ` Jakub Kicinski
2021-01-25 19:49 Chinmay Agarwal
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