[PATCH v2 3/4] module: Rework layout alignment to avoid BUG_ON()s
From: Christophe Leroy <hidden>
Date: 2022-02-22 15:12:56
Also in:
lkml
Subsystem:
module support, the rest · Maintainers:
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen, Linus Torvalds
Perform layout alignment verification up front and WARN_ON() and fail module loading instead of crashing the machine. Signed-off-by: Christophe Leroy <redacted> --- kernel/module/internal.h | 1 + kernel/module/main.c | 5 +++++ kernel/module/strict_rwx.c | 28 +++++++++++++++++++--------- 3 files changed, 25 insertions(+), 9 deletions(-)
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 276e3f49a4ae..f3dcd40f300c 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h@@ -187,6 +187,7 @@ void module_enable_nx(const struct module *mod); void module_enable_x(const struct module *mod); int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, char *secstrings, struct module *mod); +bool module_check_misalignment(const struct module *mod); #ifdef CONFIG_MODULE_SIG int module_sig_check(struct load_info *info, int flags);
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 47addf849ef7..4876e2beb5b6 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c@@ -2596,6 +2596,9 @@ static int complete_formation(struct module *mod, struct load_info *info) /* This relies on module_mutex for list integrity. */ module_bug_finalize(info->hdr, info->sechdrs, mod); + if (module_check_misalignment(mod)) + goto out_misaligned; + module_enable_ro(mod, false); module_enable_nx(mod); module_enable_x(mod);
@@ -2609,6 +2612,8 @@ static int complete_formation(struct module *mod, struct load_info *info) return 0; +out_misaligned: + err = -EINVAL; out: mutex_unlock(&module_mutex); return err;
diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
index 6b99be9e88e1..14fbea66f12f 100644
--- a/kernel/module/strict_rwx.c
+++ b/kernel/module/strict_rwx.c@@ -42,9 +42,6 @@ static void frob_text(const struct module_layout *layout, static void frob_rodata(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) { - BUG_ON(!PAGE_ALIGNED(layout->base)); - BUG_ON(!PAGE_ALIGNED(layout->text_size)); - BUG_ON(!PAGE_ALIGNED(layout->ro_size)); set_memory((unsigned long)layout->base + layout->text_size, (layout->ro_size - layout->text_size) >> PAGE_SHIFT); }
@@ -52,9 +49,6 @@ static void frob_rodata(const struct module_layout *layout, static void frob_ro_after_init(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) { - BUG_ON(!PAGE_ALIGNED(layout->base)); - BUG_ON(!PAGE_ALIGNED(layout->ro_size)); - BUG_ON(!PAGE_ALIGNED(layout->ro_after_init_size)); set_memory((unsigned long)layout->base + layout->ro_size, (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT); }
@@ -62,13 +56,29 @@ static void frob_ro_after_init(const struct module_layout *layout, static void frob_writable_data(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) { - BUG_ON(!PAGE_ALIGNED(layout->base)); - BUG_ON(!PAGE_ALIGNED(layout->ro_after_init_size)); - BUG_ON(!PAGE_ALIGNED(layout->size)); set_memory((unsigned long)layout->base + layout->ro_after_init_size, (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); } +static bool layout_check_misalignment(const struct module_layout *layout) +{ + return WARN_ON(!PAGE_ALIGNED(layout->base)) || + WARN_ON(!PAGE_ALIGNED(layout->text_size)) || + WARN_ON(!PAGE_ALIGNED(layout->ro_size)) || + WARN_ON(!PAGE_ALIGNED(layout->ro_after_init_size)) || + WARN_ON(!PAGE_ALIGNED(layout->size)); +} + +bool module_check_misalignment(const struct module *mod) +{ + if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) + return false; + + return layout_check_misalignment(&mod->core_layout) || + layout_check_misalignment(&mod->data_layout) || + layout_check_misalignment(&mod->init_layout); +} + void module_enable_x(const struct module *mod) { if (!PAGE_ALIGNED(mod->core_layout.base) ||
--
2.34.1