Messages in this thread | | | Date | Mon, 19 Apr 2021 10:49:53 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH AUTOSEL 5.10 41/46] net/rds: Avoid potential use after free in rds_send_remove_from_sock |
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Hi!
> From: Aditya Pakki <pakki001@umn.edu> > > [ Upstream commit 0c85a7e87465f2d4cbc768e245f4f45b2f299b05 ] > > In case of rs failure in rds_send_remove_from_sock(), the 'rm' resource > is freed and later under spinlock, causing potential use-after-free. > Set the free pointer to NULL to avoid undefined behavior.
This patch is crazy. It adds dead code.
> +++ b/net/rds/message.c > @@ -180,6 +180,7 @@ void rds_message_put(struct rds_message *rm) > rds_message_purge(rm); > > kfree(rm); > + rm = NULL; > } > }
We are already exiting function, changing local variable has no effect.
> +++ b/net/rds/send.c > @@ -665,7 +665,7 @@ static void rds_send_remove_from_sock(struct list_head *messages, int status) > unlock_and_drop: > spin_unlock_irqrestore(&rm->m_rs_lock, flags); > rds_message_put(rm); > - if (was_on_sock) > + if (was_on_sock && rm) > rds_message_put(rm); > }
If rm was non-NULL calling first rds_message_put (and it was, otherwise we oopsed), it is still non-NULL in second test.
Best regards, Pavel -- 'DENX Software Engineering GmbH, Managing Director: Wolfgang Denk' 'HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany'
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