diff options
| author | Kees Cook <keescook@chromium.org> | 2023-10-06 21:09:28 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2023-10-08 22:46:05 -0700 |
| commit | 381fdb73d1e2a48244de7260550e453d1003bb8e (patch) | |
| tree | 5b3232b1b4bcc7b561960a833228671d5a8e6f9f /scripts | |
| parent | c5225cd073c65a6d7e8e311ec0114792a671982a (diff) | |
randstruct: Fix gcc-plugin performance mode to stay in group
The performance mode of the gcc-plugin randstruct was shuffling struct
members outside of the cache-line groups. Limit the range to the
specified group indexes.
Cc: linux-hardening@vger.kernel.org
Cc: stable@vger.kernel.org
Reported-by: Lukas Loidolt <e1634039@student.tuwien.ac.at>
Closes: https://lore.kernel.org/all/f3ca77f0-e414-4065-83a5-ae4c4d25545d@student.tuwien.ac.at
Fixes: 313dd1b62921 ("gcc-plugins: Add the randstruct plugin")
Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/gcc-plugins/randomize_layout_plugin.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c index 951b74ba1b24..366395cab490 100644 --- a/scripts/gcc-plugins/randomize_layout_plugin.c +++ b/scripts/gcc-plugins/randomize_layout_plugin.c @@ -191,12 +191,14 @@ static void partition_struct(tree *fields, unsigned long length, struct partitio static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) { - unsigned long i, x; + unsigned long i, x, index; struct partition_group size_group[length]; unsigned long num_groups = 0; unsigned long randnum; partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups); + + /* FIXME: this group shuffle is currently a no-op. */ for (i = num_groups - 1; i > 0; i--) { struct partition_group tmp; randnum = ranval(prng_state) % (i + 1); @@ -206,11 +208,14 @@ static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prn } for (x = 0; x < num_groups; x++) { - for (i = size_group[x].start + size_group[x].length - 1; i > size_group[x].start; i--) { + for (index = size_group[x].length - 1; index > 0; index--) { tree tmp; + + i = size_group[x].start + index; if (DECL_BIT_FIELD_TYPE(newtree[i])) continue; - randnum = ranval(prng_state) % (i + 1); + randnum = ranval(prng_state) % (index + 1); + randnum += size_group[x].start; // we could handle this case differently if desired if (DECL_BIT_FIELD_TYPE(newtree[randnum])) continue; |