Messages in this thread | | | Date | Tue, 11 Jun 2019 17:38:32 +0200 | From | Greg KH <> | Subject | Re: [PATCH v3] kernel/module: Fix mem leak in module_add_modinfo_attrs |
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On Tue, Jun 11, 2019 at 10:30:56PM +0800, Yuehaibing wrote: > 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 <yuehaibing@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!
There is a simple sysfs core function that does the whole "add a whole group of files at once" in a simple manner. Perhaps you should be calling that one instead?
thanks,
greg k-h
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