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fortify: Split reporting and avoid passing string pointer

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In preparation for KUnit testing and further improvements in fortify
failure reporting, split out the report and encode the function and access
failure (read or write overflow) into a single u8 argument. This mainly
ends up saving a tiny bit of space in the data segment. For a defconfig
with FORTIFY_SOURCE enabled:

$ size gcc/vmlinux.before gcc/vmlinux.after
   text  	  data     bss     dec    	    hex filename
26132309        9760658 2195460 38088427        2452eeb gcc/vmlinux.before
26132386        9748382 2195460 38076228        244ff44 gcc/vmlinux.after

Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook
2023-04-07 12:27:13 -07:00
parent 99db710f76
commit 475ddf1fce
6 changed files with 84 additions and 28 deletions
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23
lib/string_helpers.c
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@@ -1008,10 +1008,27 @@ EXPORT_SYMBOL(__read_overflow2_field);
void __write_overflow_field(size_t avail, size_t wanted) { }
EXPORT_SYMBOL(__write_overflow_field);
void fortify_panic(const char *name)
static const char * const fortify_func_name[] = {
#define MAKE_FORTIFY_FUNC_NAME(func) [MAKE_FORTIFY_FUNC(func)] = #func
EACH_FORTIFY_FUNC(MAKE_FORTIFY_FUNC_NAME)
#undef MAKE_FORTIFY_FUNC_NAME
};
void __fortify_report(const u8 reason)
{
pr_emerg("detected buffer overflow in %s\n", name);
const u8 func = FORTIFY_REASON_FUNC(reason);
const bool write = FORTIFY_REASON_DIR(reason);
const char *name;
name = fortify_func_name[umin(func, FORTIFY_FUNC_UNKNOWN)];
WARN(1, "%s: detected buffer %s overflow\n", name, str_read_write(!write));
}
EXPORT_SYMBOL(__fortify_report);
void __fortify_panic(const u8 reason)
{
__fortify_report(reason);
BUG();
}
EXPORT_SYMBOL(fortify_panic);
EXPORT_SYMBOL(__fortify_panic);
#endif /* CONFIG_FORTIFY_SOURCE */