On Mon Nov 11, 2024 at 7:53 PM CET, Christophe Leroy wrote: > > > Le 09/11/2024 à 23:17, Daniel Gomez a écrit : >> On Sat Nov 9, 2024 at 11:35 AM CET, Christophe Leroy wrote: >>> Once module init has succeded it is too late to cancel loading. >>> If setting ro_after_init data section to read-only fails, all we >>> can do is to inform the user through a warning. >>> >>> Reported-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> >>> Closes: https://protect2.fireeye.com/v1/url?k=d3deb284-b2a35ac3-d3df39cb-74fe485fff30-288375d7d91e4ad9&q=1&e=701066ca-634d-4525-a77d-1a44451f897a&u=https%3A%2F%2Feur01.safelinks.protection.outlook.com%2F%3Furl%3Dhttps%253A%252F%252Flore.kernel.org%252Fall%252F20230915082126.4187913-1-ruanjinjie%2540huawei.com%252F%26data%3D05%257C02%257Cchristophe.leroy%2540csgroup.eu%257C26b5ca7363e54210439b08dd010c4865%257C8b87af7d86474dc78df45f69a2011bb5%257C0%257C0%257C638667874457200373%257CUnknown%257CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%253D%253D%257C0%257C%257C%257C%26sdata%3DZeJ%252F3%252B2Nx%252FBf%252FWLFEkhxKlDhZk8LNkz0fs%252Fg2xMcOjY%253D%26reserved%3D0 >>> Fixes: d1909c022173 ("module: Don't ignore errors from set_memory_XX()") >>> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> >>> --- >>> kernel/module/main.c | 6 +++--- >>> 1 file changed, 3 insertions(+), 3 deletions(-) >>> >>> diff --git a/kernel/module/main.c b/kernel/module/main.c >>> index 2de4ad7af335..1bf4b0db291b 100644 >>> --- a/kernel/module/main.c >>> +++ b/kernel/module/main.c >>> @@ -2583,7 +2583,9 @@ static noinline int do_init_module(struct module *mod) >>> #endif >>> ret = module_enable_rodata_ro_after_init(mod); >>> if (ret) >>> - goto fail_mutex_unlock; >>> + pr_warn("%s: %s() returned %d, ro_after_init data might still be writable\n", >>> + mod->name, __func__, ret); >>> + >>> mod_tree_remove_init(mod); >>> module_arch_freeing_init(mod); >>> for_class_mod_mem_type(type, init) { >>> @@ -2622,8 +2624,6 @@ static noinline int do_init_module(struct module *mod) >>> >>> return 0; >> >> I think it would make sense to propagate the error. But that would >> require changing modprobe.c. What kind of error can we expect when this >> happens? > > AFAIK, on powerpc it fails with EINVAL when > - The area is a vmalloc or module area and is a hugepage area > - The area is not vmalloc or io register and MMU is not powerpc radix MMU > > Otherwise it propagates the error from apply_to_existing_page_range(). > IIUC it will return EINVAL when it hits a leaf PTE in upper directories. Looking at that path I see we can also fail at __apply_to_page_range() -> apply_to_p4d_range() and return with -ENOMEM. My proposal was to do something like the change below in modprobe: diff --git a/tools/modprobe.c b/tools/modprobe.c index ec66e6f..8876e27 100644 --- a/tools/modprobe.c +++ b/tools/modprobe.c @@ -572,6 +572,11 @@ static int insmod_insert(struct kmod_module *mod, int flags, const char *extra_o err = 0; else { switch (err) { + case -EINVAL: + ERR("module '%s'inserted: ro_after_init data might" + "still be writable (see dmesg)\n", + kmod_module_get_name(mod)); + break; case -EEXIST: ERR("could not insert '%s': Module already in kernel\n", kmod_module_get_name(mod)); But I think these error codes may be also be reported in other parts such as simplify_symbols() so may not be a good idea after all. Maybe we just need to change the default/catch all error message in modprobe.c and to indicate/include this case: diff --git a/tools/modprobe.c b/tools/modprobe.c index ec66e6f..3647d37 100644 --- a/tools/modprobe.c +++ b/tools/modprobe.c @@ -582,7 +582,8 @@ static int insmod_insert(struct kmod_module *mod, int flags, const char *extra_o kmod_module_get_name(mod)); break; default: - ERR("could not insert '%s': %s\n", kmod_module_get_name(mod), + ERR("could not insert '%s' or inserted with error %s, " + "(see dmesg)\n", kmod_module_get_name(mod), strerror(-err)); break; } > > On other architectures it can be different, I know some architecture try > to split the pages when they hit hugepages and that can fail. Is it worth it adding an error code for this case in case we want to report it back? > > > But I believe if it works the first time it should work next time as well. Okay. It would be good to know if this is a common behaviour among different architectures. > >> >>> >>> -fail_mutex_unlock: >>> - mutex_unlock(&module_mutex); >>> fail_free_freeinit: >>> kfree(freeinit); >>> fail: >>
