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fortify: Improve buffer overflow reporting

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Improve the reporting of buffer overflows under CONFIG_FORTIFY_SOURCE to
help accelerate debugging efforts. The calculations are all just sitting
in registers anyway, so pass them along to the function to be reported.

For example, before:

  detected buffer overflow in memcpy

and after:

  memcpy: detected buffer overflow: 4096 byte read of buffer size 1

Link: https://lore.kernel.org/r/20230407192717.636137-10-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook
2023-04-07 12:27:16 -07:00
parent fa4a3f86d4
commit 3d965b33e4
6 changed files with 40 additions and 35 deletions
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9
lib/string_helpers.c
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@@ -1016,20 +1016,21 @@ static const char * const fortify_func_name[] = {
#undef MAKE_FORTIFY_FUNC_NAME
};
void __fortify_report(const u8 reason)
void __fortify_report(const u8 reason, const size_t avail, const size_t size)
{
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));
WARN(1, "%s: detected buffer overflow: %zu byte %s of buffer size %zu\n",
name, size, str_read_write(!write), avail);
}
EXPORT_SYMBOL(__fortify_report);
void __fortify_panic(const u8 reason)
void __fortify_panic(const u8 reason, const size_t avail, const size_t size)
{
__fortify_report(reason);
__fortify_report(reason, avail, size);
BUG();
}
EXPORT_SYMBOL(__fortify_panic);