Re: [Qemu-devel] [PATCH 4/8] usb: fix unbounded stack for xhci_dma_write_u32s

[Peter Xu]

On Wed, Mar 09, 2016 at 08:53:19AM +0100, Paolo Bonzini wrote:
> 
> 
> On 09/03/2016 06:08, Peter Xu wrote:
> > pxdev:bin# gcc -v
> > Using built-in specs.
> > COLLECT_GCC=/bin/gcc
> > COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/lto-wrapper
> > Target: x86_64-redhat-linux
> > Configured with: ../configure --prefix=/usr --mandir=/usr/share/man 
> > --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla 
> > --enable-bootstrap --enable-shared --enable-threads=posix 
> > --enable-checking=release --with-system-zlib --enable-__cxa_atexit 
> > --disable-libunwind-exceptions --enable-gnu-unique-object 
> > --enable-linker-build-id --with-linker-hash-style=gnu 
> > --enable-languages=c,c++,objc,obj-c++,java,fortran,ada,go,lto 
> > --enable-plugin --enable-initfini-array --disable-libgcj 
> > --with-isl=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat-linux/isl-install
> >  
> > --with-cloog=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat-linux/cloog-install
> >  --enable-gnu-indirect-function --with-tune=generic --with-arch_32=x86-64 
> > --build=x86_64-redhat-linux
> > Thread model: posix
> > gcc version 4.8.5 20150623 (Red Hat 4.8.5-4) (GCC)
> > 
> > Do you know why "might not be inlinable"? Failed to figure it out
> > myself as mentioned in cover letter..
> 
> It's just a difference in compiler versions.  But ARRAY_SIZE should be
> enough to fix it.

It's dynamically allocated in stack, can we still use ARRAY_SIZE in
this case?

Maybe for this case, best to use both stack and heap? malloc only if
buffer big enough.

Peter