Re: [PATCH 1/7] modpost: add strict white-listing when referencing sections.

From: Rusty Russell
Date: Thu Mar 19 2015 - 21:45:21 EST


Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx> writes:
> Prints a warning when a section references a section outside a strict
> white-list. This will be useful to print a warning if __ex_table
> references a non-executable section.

Hi Quentin,

Really pleasant to read these patches; nice work!

> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index d439856..7094a57 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -925,7 +925,8 @@ enum mismatch {
>
> struct sectioncheck {
> const char *fromsec[20];
> - const char *tosec[20];
> + const char *bad_tosec[20];
> + const char *good_tosec[20];
> enum mismatch mismatch;
> const char *symbol_white_list[20];

My only gripe is that these fields are undocumented. You maintain
the status quo, but some comments indicating what the mean would be
nice. Perhaps as a separate patch.

In case you need it (for the whole series):
Acked-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

Thanks,
Rusty.

> };
> @@ -936,19 +937,19 @@ static const struct sectioncheck sectioncheck[] = {
> */
> {
> .fromsec = { TEXT_SECTIONS, NULL },
> - .tosec = { ALL_INIT_SECTIONS, NULL },
> + .bad_tosec = { ALL_INIT_SECTIONS, NULL },
> .mismatch = TEXT_TO_ANY_INIT,
> .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
> },
> {
> .fromsec = { DATA_SECTIONS, NULL },
> - .tosec = { ALL_XXXINIT_SECTIONS, NULL },
> + .bad_tosec = { ALL_XXXINIT_SECTIONS, NULL },
> .mismatch = DATA_TO_ANY_INIT,
> .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
> },
> {
> .fromsec = { DATA_SECTIONS, NULL },
> - .tosec = { INIT_SECTIONS, NULL },
> + .bad_tosec = { INIT_SECTIONS, NULL },
> .mismatch = DATA_TO_ANY_INIT,
> .symbol_white_list = {
> "*_template", "*_timer", "*_sht", "*_ops",
> @@ -957,54 +958,54 @@ static const struct sectioncheck sectioncheck[] = {
> },
> {
> .fromsec = { TEXT_SECTIONS, NULL },
> - .tosec = { ALL_EXIT_SECTIONS, NULL },
> + .bad_tosec = { ALL_EXIT_SECTIONS, NULL },
> .mismatch = TEXT_TO_ANY_EXIT,
> .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
> },
> {
> .fromsec = { DATA_SECTIONS, NULL },
> - .tosec = { ALL_EXIT_SECTIONS, NULL },
> + .bad_tosec = { ALL_EXIT_SECTIONS, NULL },
> .mismatch = DATA_TO_ANY_EXIT,
> .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
> },
> /* Do not reference init code/data from meminit code/data */
> {
> .fromsec = { ALL_XXXINIT_SECTIONS, NULL },
> - .tosec = { INIT_SECTIONS, NULL },
> + .bad_tosec = { INIT_SECTIONS, NULL },
> .mismatch = XXXINIT_TO_SOME_INIT,
> .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
> },
> /* Do not reference exit code/data from memexit code/data */
> {
> .fromsec = { ALL_XXXEXIT_SECTIONS, NULL },
> - .tosec = { EXIT_SECTIONS, NULL },
> + .bad_tosec = { EXIT_SECTIONS, NULL },
> .mismatch = XXXEXIT_TO_SOME_EXIT,
> .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
> },
> /* Do not use exit code/data from init code */
> {
> .fromsec = { ALL_INIT_SECTIONS, NULL },
> - .tosec = { ALL_EXIT_SECTIONS, NULL },
> + .bad_tosec = { ALL_EXIT_SECTIONS, NULL },
> .mismatch = ANY_INIT_TO_ANY_EXIT,
> .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
> },
> /* Do not use init code/data from exit code */
> {
> .fromsec = { ALL_EXIT_SECTIONS, NULL },
> - .tosec = { ALL_INIT_SECTIONS, NULL },
> + .bad_tosec = { ALL_INIT_SECTIONS, NULL },
> .mismatch = ANY_EXIT_TO_ANY_INIT,
> .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
> },
> {
> .fromsec = { ALL_PCI_INIT_SECTIONS, NULL },
> - .tosec = { INIT_SECTIONS, NULL },
> + .bad_tosec = { INIT_SECTIONS, NULL },
> .mismatch = ANY_INIT_TO_ANY_EXIT,
> .symbol_white_list = { NULL },
> },
> /* Do not export init/exit functions or data */
> {
> .fromsec = { "__ksymtab*", NULL },
> - .tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL },
> + .bad_tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL },
> .mismatch = EXPORT_TO_INIT_EXIT,
> .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
> }
> @@ -1018,9 +1019,12 @@ static const struct sectioncheck *section_mismatch(
> const struct sectioncheck *check = &sectioncheck[0];
>
> for (i = 0; i < elems; i++) {
> - if (match(fromsec, check->fromsec) &&
> - match(tosec, check->tosec))
> - return check;
> + if (match(fromsec, check->fromsec)) {
> + if (check->bad_tosec[0] && match(tosec, check->bad_tosec))
> + return check;
> + if (check->good_tosec[0] && !match(tosec, check->good_tosec))
> + return check;
> + }
> check++;
> }
> return NULL;
> --
> 2.0.5
>
> --
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