[RESEND PATCH v2] modules: wait do_free_init correctly
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STALE967d
From: Changbin Du <hidden>
Date: 2024-01-29 02:03:21
Also in:
lkml
Subsystem:
module support, the rest · Maintainers:
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen, Linus Torvalds
The commit 1a7b7d922081 ("modules: Use vmalloc special flag") moves
do_free_init() into a global workqueue instead of call_rcu(). So now
rcu_barrier() can not ensure that do_free_init has completed. We should
wait it via flush_work().
Without this fix, we still could encounter false positive reports in
W+X checking, and rcu synchronization is unnecessary.
Fixes: 1a7b7d922081 ("modules: Use vmalloc special flag")
Signed-off-by: Changbin Du <redacted>
Cc: Xiaoyi Su <redacted>
---
v2: fix compilation issue for no CONFIG_MODULES found by 0-DAY.
---
include/linux/moduleloader.h | 8 ++++++++
init/main.c | 5 +++--
kernel/module/main.c | 5 +++++
3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
index 001b2ce83832..89b1e0ed9811 100644
--- a/include/linux/moduleloader.h
+++ b/include/linux/moduleloader.h@@ -115,6 +115,14 @@ int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *mod); +#ifdef CONFIG_MODULES +void flush_module_init_free_work(void); +#else +static inline void flush_module_init_free_work(void) +{ +} +#endif + /* Any cleanup needed when module leaves. */ void module_arch_cleanup(struct module *mod);
diff --git a/init/main.c b/init/main.c
index e24b0780fdff..f0b7e21ac67f 100644
--- a/init/main.c
+++ b/init/main.c@@ -99,6 +99,7 @@ #include <linux/init_syscalls.h> #include <linux/stackdepot.h> #include <linux/randomize_kstack.h> +#include <linux/moduleloader.h> #include <net/net_namespace.h> #include <asm/io.h>
@@ -1402,11 +1403,11 @@ static void mark_readonly(void) if (rodata_enabled) { /* * load_module() results in W+X mappings, which are cleaned - * up with call_rcu(). Let's make sure that queued work is + * up with init_free_wq. Let's make sure that queued work is * flushed so that we don't hit false positives looking for * insecure pages which are W+X. */ - rcu_barrier(); + flush_module_init_free_work(); mark_rodata_ro(); rodata_test(); } else
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 36681911c05a..ea66b5c2a2a1 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c@@ -2489,6 +2489,11 @@ static void do_free_init(struct work_struct *w) } } +void flush_module_init_free_work(void) +{ + flush_work(&init_free_wq); +} + #undef MODULE_PARAM_PREFIX #define MODULE_PARAM_PREFIX "module." /* Default value for module->async_probe_requested */
--
2.25.1