SIGSEGV on large displays

[Jonah Graham]

(I submitted an Apport on this - but I don't know how to tie the two together, or where the Apport report went.)

When using Eclipse with VNC and VNC server running with a high resolution -geometry (e.g I used 3840x2000) I have regular X server crashes with Eclipse when Eclipse is fullscreen (SIGSEGV in Dispatch()).

I tracked down the problem to being an alloca call that was much bigger than the current stack size in ProcShmGetImage in Xvnc/programs/Xserver/Xext/shm.c. In my case I was seeing the length variable requesting about 16MB.

I suppose a fix is to change that particular ALLOCATE_LOCAL to a normal malloc (Xmalloc??) or to disable alloca use globally.

My workaround was to change the stack size to something much bigger (ulimit -s 50000)