Re: [PATCH] uprobes: ensure that uprobe->offset and ->ref_ctr_offset are properly aligned

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 6 May 2020 10:59:55 +0530
Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote:

> * Oleg Nesterov <oleg@redhat.com> [2020-05-04 18:47:25]:
> 
> > uprobe_write_opcode() must not cross page boundary; prepare_uprobe()
> > relies on arch_uprobe_analyze_insn() which should validate "vaddr" but
> > some architectures (csky, s390, and sparc) don't do this.
> > 
> > We can remove the BUG_ON() check in prepare_uprobe() and validate the
> > offset early in __uprobe_register(). The new IS_ALIGNED() check matches
> > the alignment check in arch_prepare_kprobe() on supported architectures,
> > so I think that all insns must be aligned to UPROBE_SWBP_INSN_SIZE.
> > 
> > Another problem is __update_ref_ctr() which was wrong from the very
> > beginning, it can read/write outside of kmap'ed page unless "vaddr" is
> > aligned to sizeof(short), __uprobe_register() should check this too.
> > 
> > Cc: stable@vger.kernel.org
> > Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> > Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> > Signed-off-by: Oleg Nesterov <oleg@redhat.com>  
> 
> Thanks Oleg.
> 
> Looks good to me.
> 
> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> > ---  
> 

Thanks Oleg, Srikar and Sven.

As this is in the kernel/events/ directory, I'm guessing it should be taken
through the tip tree?

-- Steve