Messages in this thread | | | From | Sergey Senozhatsky <> | Date | Mon, 25 May 2020 18:11:57 +0900 | Subject | Re: [PATCH] twist: allow converting pr_devel()/pr_debug() into printk(KERN_DEBUG) |
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On (20/05/25 10:42), Petr Mladek wrote: > On Sun 2020-05-24 23:50:34, Tetsuo Handa wrote: > > syzbot found a NULL pointer dereference bug inside mptcp_recvmsg() due to > > ssock == NULL, but this bug manifested inside selinux_socket_recvmsg() > > because pr_debug() was no-op [1]. > > > > pr_debug("fallback-read subflow=%p", > > mptcp_subflow_ctx(ssock->sk)); > > copied = sock_recvmsg(ssock, msg, flags); > > The NULL pointer deference was found even without this patch. > This patch would just cause that it will manifest itself on another > place. What is the benefit, please?
Right, I don't get this patch. A NULL-deref is still a NULL pointer deref. pr_debug() will fault reading one byte from the address and print something like "fallback-read subflow=(efault)" to printk-safe buffer, but then sock_recvmsg() is still going to do its thing.
-ss
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