Le jeudi 08 septembre 2011 à 01:37 -0700, Tim Chen a écrit :
On Thu, 2011-09-08 at 15:21 +0200, Eric Dumazet wrote:
quoted
Le jeudi 08 septembre 2011 à 11:59 +0200, Sedat Dilek a écrit :
quoted
I have tested this fixup patch on i386.
Can we have a separate patch with corrected descriptive text?
Thanks to all involved people.
Here it is :
[PATCH net-next v3] af_unix: Fix use-after-free crashes
Commit 0856a30409 (Scm: Remove unnecessary pid & credential references
in Unix socket's send and receive path) introduced an use-after-free
bug.
We are allowed to steal the references to pid/cred only in the last skb
sent from unix_stream_sendmsg(), because first skbs might be consumed by
the receiver before we finish our sendmsg() call.
Remove scm_release() helper, since its cleaner to clear pid/cred fields
in unix_scm_to_skb() when we steal them.
Based on prior patches from Yan Zheng and Tim Chen
Signed-off-by: Eric Dumazet <redacted>
Reported-by: Jiri Slaby <redacted>
Tested-by: Sedat Dilek <redacted>
Tested-by: Valdis Kletnieks <redacted>
---
Thanks.
Acked-by: Tim Chen <redacted>
Now we have to fix a bug in unix_stream_recvmsg() as well.
consume_skb() call actually releases pid/cred references, and we can use
them after their eventual freeing.
Keep also in mind that receiver can provides a too short user buffer,
and skb can be put back to head of sk_receive_queue
Tim, your 0856a304091b33 commit introduced a lot of bugs, I was right
asking a revert.
If we revert your patch, my litle patch (af_unix: dont send
SCM_CREDENTIALS by default) is enough to solve performance problems.