From 25499e2139b248eef1b89148002ade27f0223ba9 Mon Sep 17 00:00:00 2001 From: Ryan Moeller Date: Fri, 31 Jul 2020 12:17:37 -0400 Subject: [PATCH] lua: Increase reserved stack space for FreeBSD in debug config FreeBSD uses more stack space in debug configurations and can overflow the stack while formatting the error message when the call depth limit of 20 frames is reached. This is readily reproduced by running the gsub recursion test with increased kstack size. I hit the panic with 16 pages per kstack, and noticed it go away when bumped to 17. Reserve an additional 64 bytes on the stack when building for FreeBSD. This is enough to avoid the panic with a deep stack while not wasting too much space when the default stack size is used. Reviewed-by: Matt Ahrens Reviewed-by: Brian Behlendorf Signed-off-by: Ryan Moeller Closes #10634 --- module/lua/llimits.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/module/lua/llimits.h b/module/lua/llimits.h index 177092fbc2..25466f14ed 100644 --- a/module/lua/llimits.h +++ b/module/lua/llimits.h @@ -126,7 +126,16 @@ typedef LUAI_UACNUMBER l_uacNumber; * Minimum amount of available stack space (in bytes) to make a C call. With * gsub() recursion, the stack space between each luaD_call() is 1256 bytes. */ +#if defined(__FreeBSD__) +/* + * FreeBSD needs a few extra bytes in unoptimized debug builds to avoid a + * double-fault handling the error when the max call depth is exceeded just + * before the C stack runs out. 64 bytes seems to do the trick. + */ +#define LUAI_MINCSTACK 4160 +#else #define LUAI_MINCSTACK 4096 +#endif /* ** maximum number of upvalues in a closure (both C and Lua). (Value