Re: [PATCH V2 net-next] rds: do not call ->conn_alloc with GFP_KERNEL

[David Miller]

From: Sowmini Varadhan 
Date: Tue, 13 Feb 2018 09:05:44 -0800

> Commit ebeeb1ad9b8a ("rds: tcp: use rds_destroy_pending() to synchronize
> netns/module teardown and rds connection/workq management")
> adds an rcu read critical section to __rd_conn_create. The
> memory allocations in that critcal section need to use
> GFP_ATOMIC to avoid sleeping.
> 
> This patch was verified with syzkaller reproducer.
> 
> Fixes: ebeeb1ad9b8a ("rds: tcp: use rds_destroy_pending() to synchronize
>netns/module teardown and rds connection/workq management")
> Reported-by: syzbot+a0564419941aaae3f...@syzkaller.appspotmail.com
> Signed-off-by: Sowmini Varadhan 
> ---
> v2: do not over-engineer. Keep the gfp arg to ->conn_alloc simple.

Already applied to 'net', no need to send this again.

[PATCH V2 net-next] rds: do not call ->conn_alloc with GFP_KERNEL

[Sowmini Varadhan]

Commit ebeeb1ad9b8a ("rds: tcp: use rds_destroy_pending() to synchronize
netns/module teardown and rds connection/workq management")
adds an rcu read critical section to __rd_conn_create. The
memory allocations in that critcal section need to use
GFP_ATOMIC to avoid sleeping.

This patch was verified with syzkaller reproducer.

Fixes: ebeeb1ad9b8a ("rds: tcp: use rds_destroy_pending() to synchronize
   netns/module teardown and rds connection/workq management")
Reported-by: syzbot+a0564419941aaae3f...@syzkaller.appspotmail.com
Signed-off-by: Sowmini Varadhan 
---
v2: do not over-engineer. Keep the gfp arg to ->conn_alloc simple.

 net/rds/connection.c |2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/rds/connection.c b/net/rds/connection.c
index 94e190f..2da3176 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -224,7 +224,7 @@ static void __rds_conn_path_init(struct rds_connection 
*conn,
if (rds_destroy_pending(conn))
ret = -ENETDOWN;
else
-   ret = trans->conn_alloc(conn, gfp);
+   ret = trans->conn_alloc(conn, GFP_ATOMIC);
if (ret) {
rcu_read_unlock();
kfree(conn->c_path);
-- 
1.7.1

Re: [PATCH V2 net-next] rds: do not call ->conn_alloc with GFP_KERNEL

[Santosh Shilimkar]

On 2/13/2018 9:05 AM, Sowmini Varadhan wrote:

Commit ebeeb1ad9b8a ("rds: tcp: use rds_destroy_pending() to synchronize
netns/module teardown and rds connection/workq management")
adds an rcu read critical section to __rd_conn_create. The
memory allocations in that critcal section need to use
GFP_ATOMIC to avoid sleeping.

This patch was verified with syzkaller reproducer.

Fixes: ebeeb1ad9b8a ("rds: tcp: use rds_destroy_pending() to synchronize
netns/module teardown and rds connection/workq management")
Reported-by: syzbot+a0564419941aaae3f...@syzkaller.appspotmail.com
Signed-off-by: Sowmini Varadhan 
---

Acked-by: Santosh Shilimkar