From e656f46bdc55d13c06d2d6e46e4b4b7c0f832d6d Mon Sep 17 00:00:00 2001 From: Miroslav Benes Date: Tue, 27 Oct 2020 15:03:36 +0100 Subject: module: set MODULE_STATE_GOING state when a module fails to load [ Upstream commit 5e8ed280dab9eeabc1ba0b2db5dbe9fe6debb6b5 ] If a module fails to load due to an error in prepare_coming_module(), the following error handling in load_module() runs with MODULE_STATE_COMING in module's state. Fix it by correctly setting MODULE_STATE_GOING under "bug_cleanup" label. Signed-off-by: Miroslav Benes Signed-off-by: Jessica Yu Signed-off-by: Sasha Levin --- kernel/module.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/module.c') diff --git a/kernel/module.c b/kernel/module.c index 2f695b6e1a3e..dcfc811d9ae2 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3589,6 +3589,7 @@ static int load_module(struct load_info *info, const char __user *uargs, return do_init_module(mod); bug_cleanup: + mod->state = MODULE_STATE_GOING; /* module_bug_cleanup needs module_mutex protection */ mutex_lock(&module_mutex); module_bug_cleanup(mod); -- cgit v1.2.3 From 8e276172803340b6dd2368c817ccaeb3870947c4 Mon Sep 17 00:00:00 2001 From: Jessica Yu Date: Fri, 27 Nov 2020 10:09:39 +0100 Subject: module: delay kobject uevent until after module init call [ Upstream commit 38dc717e97153e46375ee21797aa54777e5498f3 ] Apparently there has been a longstanding race between udev/systemd and the module loader. Currently, the module loader sends a uevent right after sysfs initialization, but before the module calls its init function. However, some udev rules expect that the module has initialized already upon receiving the uevent. This race has been triggered recently (see link in references) in some systemd mount unit files. For instance, the configfs module creates the /sys/kernel/config mount point in its init function, however the module loader issues the uevent before this happens. sys-kernel-config.mount expects to be able to mount /sys/kernel/config upon receipt of the module loading uevent, but if the configfs module has not called its init function yet, then this directory will not exist and the mount unit fails. A similar situation exists for sys-fs-fuse-connections.mount, as the fuse sysfs mount point is created during the fuse module's init function. If udev is faster than module initialization then the mount unit would fail in a similar fashion. To fix this race, delay the module KOBJ_ADD uevent until after the module has finished calling its init routine. References: https://github.com/systemd/systemd/issues/17586 Reviewed-by: Greg Kroah-Hartman Tested-By: Nicolas Morey-Chaisemartin Signed-off-by: Jessica Yu Signed-off-by: Sasha Levin --- kernel/module.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel/module.c') diff --git a/kernel/module.c b/kernel/module.c index dcfc811d9ae2..e6afc950357a 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1779,7 +1779,6 @@ static int mod_sysfs_init(struct module *mod) if (err) mod_kobject_put(mod); - /* delay uevent until full sysfs population */ out: return err; } @@ -1813,7 +1812,6 @@ static int mod_sysfs_setup(struct module *mod, add_sect_attrs(mod, info); add_notes_attrs(mod, info); - kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD); return 0; out_unreg_param: @@ -3301,6 +3299,9 @@ static noinline int do_init_module(struct module *mod) blocking_notifier_call_chain(&module_notify_list, MODULE_STATE_LIVE, mod); + /* Delay uevent until module has finished its init routine */ + kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD); + /* * We need to finish all async code before the module init sequence * is done. This has potential to deadlock. For example, a newly -- cgit v1.2.3 From 250704fae6c57834326f5579c0545d0651fa2673 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Fri, 15 Jan 2021 11:52:22 -0800 Subject: module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols commit ebfac7b778fac8b0e8e92ec91d0b055f046b4604 upstream. clang-12 -fno-pic (since https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` on x86. The two forms should have identical behaviors on x86-64 but the former causes GNU as<2.37 to produce an unreferenced undefined symbol _GLOBAL_OFFSET_TABLE_. (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the linker behavior is identical as far as Linux kernel is concerned.) Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for external function calls on x86. Note: ld -z defs and dynamic loaders do not error for unreferenced undefined symbols so the module loader is reading too much. If we ever need to ignore more symbols, the code should be refactored to ignore unreferenced symbols. Cc: Link: https://github.com/ClangBuiltLinux/linux/issues/1250 Link: https://sourceware.org/bugzilla/show_bug.cgi?id=27178 Reported-by: Marco Elver Reviewed-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Tested-by: Marco Elver Signed-off-by: Fangrui Song Signed-off-by: Jessica Yu Signed-off-by: Greg Kroah-Hartman --- kernel/module.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'kernel/module.c') diff --git a/kernel/module.c b/kernel/module.c index e6afc950357a..d84f5e38456f 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2107,6 +2107,21 @@ static int verify_export_symbols(struct module *mod) return 0; } +static bool ignore_undef_symbol(Elf_Half emachine, const char *name) +{ + /* + * On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as + * before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ on x86-64. + * i386 has a similar problem but may not deserve a fix. + * + * If we ever have to ignore many symbols, consider refactoring the code to + * only warn if referenced by a relocation. + */ + if (emachine == EM_386 || emachine == EM_X86_64) + return !strcmp(name, "_GLOBAL_OFFSET_TABLE_"); + return false; +} + /* Change all symbols so that st_value encodes the pointer directly. */ static int simplify_symbols(struct module *mod, const struct load_info *info) { @@ -2148,8 +2163,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) break; } - /* Ok if weak. */ - if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) + /* Ok if weak or ignored. */ + if (!ksym && + (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || + ignore_undef_symbol(info->hdr->e_machine, name))) break; pr_warn("%s: Unknown symbol %s (err %li)\n", -- cgit v1.2.3