Messages in this thread | | | Date | Thu, 28 May 2020 13:06:46 +0200 | From | Petr Mladek <> | Subject | Re: [PATCH v2] twist: allow converting pr_devel()/pr_debug() into snprintf() |
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On Thu 2020-05-28 15:56:03, 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); > > Thus, let's allow fuzzers to always evaluate pr_devel()/pr_debug() > messages, by redirecting no-op pr_devel()/pr_debug() calls to snprintf(). > > [1] https://syzkaller.appspot.com/bug?id=12be9aa373be9d8727cdd172f190de39528a413a > > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Cc: Petr Mladek <pmladek@suse.com> > Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Ondrej Mosnacek <omosnace@redhat.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > --- > include/linux/dev_printk.h | 16 ++++++++++++++++ > include/linux/dynamic_debug.h | 14 ++++++++++++-- > include/linux/printk.h | 10 ++++++++++ > lib/Kconfig.twist | 12 ++++++++++++ > 4 files changed, 50 insertions(+), 2 deletions(-)
I am fine with pushing this into linux-next for testing purposes. But I am against pushing this to Linus' tree in this form.
Now, it requires lib/Kconfig.twist that is added by a patch in Andrew's tree. One approach is to push this into linux-next via Andrew's -mm tree.
Another possibility would be to remove lib/Kconfig.twist changes from this patch and replace CONFIG_TWIST_ALWAYS_EVALUATE_PRINTK_ARGUMENTS with CONFIG_TWIST_FOR_SYZKALLER_TESTING. Then I could push it into linux-next via printk/linux.git tree.
Best Regards, Petr
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