On 2019/6/11 21:33, Jessica Yu wrote: > +++ YueHaibing [03/06/19 22:45 +0800]: >> In module_add_modinfo_attrs if sysfs_create_file >> fails, we forget to free allocated modinfo_attrs >> and roll back the sysfs files. >> >> Fixes: 03e88ae1b13d ("[PATCH] fix module sysfs files reference counting") >> Signed-off-by: YueHaibing <yuehaib...@huawei.com> >> --- >> v3: reuse module_remove_modinfo_attrs >> v2: free from '--i' instead of 'i--' >> --- >> kernel/module.c | 21 ++++++++++++++++----- >> 1 file changed, 16 insertions(+), 5 deletions(-) >> >> diff --git a/kernel/module.c b/kernel/module.c >> index 80c7c09..c6b8912 100644 >> --- a/kernel/module.c >> +++ b/kernel/module.c >> @@ -1697,6 +1697,8 @@ static int add_usage_links(struct module *mod) >> return ret; >> } >> >> +static void module_remove_modinfo_attrs(struct module *mod, int end); >> + >> static int module_add_modinfo_attrs(struct module *mod) >> { >> struct module_attribute *attr; >> @@ -1711,24 +1713,33 @@ static int module_add_modinfo_attrs(struct module >> *mod) >> return -ENOMEM; >> >> temp_attr = mod->modinfo_attrs; >> - for (i = 0; (attr = modinfo_attrs[i]) && !error; i++) { >> + for (i = 0; (attr = modinfo_attrs[i]); i++) { >> if (!attr->test || attr->test(mod)) { >> memcpy(temp_attr, attr, sizeof(*temp_attr)); >> sysfs_attr_init(&temp_attr->attr); >> error = sysfs_create_file(&mod->mkobj.kobj, >> &temp_attr->attr); >> + if (error) >> + goto error_out; >> ++temp_attr; >> } >> } >> + >> + return 0; >> + >> +error_out: >> + module_remove_modinfo_attrs(mod, --i); > > Gah, I think there is another issue here - if sysfs_create_file() > fails on the first iteration of the loop (so i = 0), then we will go > to error_out and end up calling module_remove_modinfo_attrs(mod, -1), > which, for i = 0, will call sysfs_remove_file() since attr->attr.name > had already been set before the failed call to sysfs_create_file(). > Perhaps we need to check that i > 0 before calling > module_remove_modinfo_attrs() under error_out?
Indeed, this should be checked, thanks! > >> return error; >> } >> >> -static void module_remove_modinfo_attrs(struct module *mod) >> +static void module_remove_modinfo_attrs(struct module *mod, int end) >> { >> struct module_attribute *attr; >> int i; >> >> for (i = 0; (attr = &mod->modinfo_attrs[i]); i++) { >> + if (end >= 0 && i > end) >> + break; >> /* pick a field to test for end of list */ >> if (!attr->attr.name) >> break; >> @@ -1816,7 +1827,7 @@ static int mod_sysfs_setup(struct module *mod, >> return 0; >> >> out_unreg_modinfo_attrs: >> - module_remove_modinfo_attrs(mod); >> + module_remove_modinfo_attrs(mod, -1); >> out_unreg_param: >> module_param_sysfs_remove(mod); >> out_unreg_holders: >> @@ -1852,7 +1863,7 @@ static void mod_sysfs_fini(struct module *mod) >> { >> } >> >> -static void module_remove_modinfo_attrs(struct module *mod) >> +static void module_remove_modinfo_attrs(struct module *mod, int end) >> { >> } >> >> @@ -1868,7 +1879,7 @@ static void init_param_lock(struct module *mod) >> static void mod_sysfs_teardown(struct module *mod) >> { >> del_usage_links(mod); >> - module_remove_modinfo_attrs(mod); >> + module_remove_modinfo_attrs(mod, -1); >> module_param_sysfs_remove(mod); >> kobject_put(mod->mkobj.drivers_dir); >> kobject_put(mod->holders_dir); >> -- >> 1.8.3.1 >> >> > > . >