Hi!
From: Kees Cook keescook@chromium.org
[ Upstream commit 3e1730842f142add55dc658929221521a9ea62b6 ]
Clang produces a false positive when building with CONFIG_FORTIFY_SOURCE=y and CONFIG_UBSAN_BOUNDS=y when operating on an array with a dynamic offset. Work around this by using a direct assignment of an empty instance. Avoids this warning:
../include/linux/fortify-string.h:309:4: warning: call to __write_overflow_field declared with 'warn ing' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wat tribute-warning] __write_overflow_field(p_size_field, size); ^
which was isolated to the memset() call in xen_load_idt().
Note that this looks very much like another bug that was worked around: https://github.com/ClangBuiltLinux/linux/issues/1592
We don't have CONFIG_UBSAN_BOUNDS in 4.19, so maybe we don't need this one?
Best regards, Pavel
+++ b/arch/x86/xen/enlighten_pv.c @@ -752,6 +752,7 @@ static void xen_load_idt(const struct desc_ptr *desc) { static DEFINE_SPINLOCK(lock); static struct trap_info traps[257];
- static const struct trap_info zero = { }; unsigned out;
trace_xen_cpu_load_idt(desc); @@ -761,7 +762,7 @@ static void xen_load_idt(const struct desc_ptr *desc) memcpy(this_cpu_ptr(&idt_desc), desc, sizeof(idt_desc)); out = xen_convert_trap_info(desc, traps, false);
- memset(&traps[out], 0, sizeof(traps[0]));
- traps[out] = zero;
xen_mc_flush(); if (HYPERVISOR_set_trap_table(traps)) -- 2.35.1