On Tue, May 18 2021 at 13:03, Chang S. Bae wrote: > During signal entry, the kernel pushes data onto the normal userspace > stack. On x86, the data pushed onto the user stack includes XSAVE state, > which has grown over time as new features and larger registers have been > added to the architecture. > > MINSIGSTKSZ is a constant provided in the kernel signal.h headers and > typically distributed in lib-dev(el) packages, e.g. [1]. Its value is > compiled into programs and is part of the user/kernel ABI. The MINSIGSTKSZ > constant indicates to userspace how much data the kernel expects to push on > the user stack, [2][3]. > > However, this constant is much too small and does not reflect recent > additions to the architecture. For instance, when AVX-512 states are in > use, the signal frame size can be 3.5KB while MINSIGSTKSZ remains 2KB. > > The bug report [4] explains this as an ABI issue. The small MINSIGSTKSZ can > cause user stack overflow when delivering a signal. Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
