On Wed, Dec 23, 2020 at 2:57 AM Chang S. Bae <chang.seok.bae@xxxxxxxxx> wrote: > The kernel pushes data on the userspace stack when entering a signal. If > using a sigaltstack(), the kernel precisely knows the user stack size. > > When the kernel knows that the user stack is too small, avoid the overflow > and do an immediate SIGSEGV instead. > > This overflow is known to occur on systems with large XSAVE state. The > effort to increase the size typically used for altstacks reduces the > frequency of these overflows, but this approach is still useful for legacy > binaries. > > Suggested-by: Jann Horn <jannh@xxxxxxxxxx> > Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx> > Reviewed-by: Len Brown <len.brown@xxxxxxxxx> > Cc: Jann Horn <jannh@xxxxxxxxxx> > Cc: x86@xxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx Reviewed-by: Jann Horn <jannh@xxxxxxxxxx>
