Re: [ 09/56] x86-32: Fix invalid stack address while in softirq

[Greg Kroah-Hartman]

On Tue, Dec 04, 2012 at 11:56:46AM -0200, Herton Ronaldo Krzesinski wrote:
> On Fri, Nov 30, 2012 at 10:55:01AM -0800, Greg Kroah-Hartman wrote:
> > 3.4-stable review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Robert Richter <robert.richter@xxxxxxx>
> > 
> > commit 1022623842cb72ee4d0dbf02f6937f38c92c3f41 upstream.
> > 
> > In 32 bit the stack address provided by kernel_stack_pointer() may
> > point to an invalid range causing NULL pointer access or page faults
> > while in NMI (see trace below). This happens if called in softirq
> > context and if the stack is empty. The address at &regs->sp is then
> > out of range.
> > 
> > Fixing this by checking if regs and &regs->sp are in the same stack
> > context. Otherwise return the previous stack pointer stored in struct
> > thread_info. If that address is invalid too, return address of regs.
> > 
> 
> This also makes latest 3.4.y build fail with oprofile on i386, needs
> also EXPORT_SYMBOL for kernel_stack_pointer (commit
> cb57a2b4cff7edf2a4e32c0163200e9434807e0a)

Sorry, now fixed with 3.4.22
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