[PATCH v2 40/44] ubsan: Fix objtool UACCESS warns
From: Peter Zijlstra <peterz@infradead.org>
Date: 2022-09-19 10:21:21
Also in:
linux-acpi, linux-alpha, linux-arch, linux-arm-msm, linux-clk, linux-m68k, linux-mips, linux-omap, linux-perf-users, linux-pm, linux-riscv, linux-s390, linux-sh, linux-tegra, linux-um, lkml, loongarch, sparclinux, virtualization
clang-14 allyesconfig gives: vmlinux.o: warning: objtool: emulator_cmpxchg_emulated+0x705: call to __ubsan_handle_load_invalid_value() with UACCESS enabled vmlinux.o: warning: objtool: paging64_update_accessed_dirty_bits+0x39e: call to __ubsan_handle_load_invalid_value() with UACCESS enabled vmlinux.o: warning: objtool: paging32_update_accessed_dirty_bits+0x390: call to __ubsan_handle_load_invalid_value() with UACCESS enabled vmlinux.o: warning: objtool: ept_update_accessed_dirty_bits+0x43f: call to __ubsan_handle_load_invalid_value() with UACCESS enabled Add the required eflags save/restore and whitelist the thing. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- lib/ubsan.c | 5 ++++- tools/objtool/check.c | 1 + 2 files changed, 5 insertions(+), 1 deletion(-)
--- a/lib/ubsan.c
+++ b/lib/ubsan.c@@ -340,9 +340,10 @@ void __ubsan_handle_load_invalid_value(v { struct invalid_value_data *data = _data; char val_str[VALUE_LENGTH]; + unsigned long ua_flags = user_access_save(); if (suppress_report(&data->location)) - return; + goto out; ubsan_prologue(&data->location, "invalid-load");
@@ -352,6 +353,8 @@ void __ubsan_handle_load_invalid_value(v val_str, data->type->type_name); ubsan_epilogue(); +out: + user_access_restore(ua_flags); } EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); --- a/tools/objtool/check.c +++ b/tools/objtool/check.c
@@ -1068,6 +1068,7 @@ static const char *uaccess_safe_builtin[ "__ubsan_handle_type_mismatch", "__ubsan_handle_type_mismatch_v1", "__ubsan_handle_shift_out_of_bounds", + "__ubsan_handle_load_invalid_value", /* misc */ "csum_partial_copy_generic", "copy_mc_fragile",