Messages in this thread | | | Subject | Re: [PATCH 00/11] fix memory leak while kset_register() fails | From | Yang Yingliang <> | Date | Fri, 21 Oct 2022 15:25:51 +0800 |
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Hi,
On 2022/10/21 13:29, Luben Tuikov wrote: > On 2022-10-20 22:20, Yang Yingliang wrote: >> The previous discussion link: >> https://lore.kernel.org/lkml/0db486eb-6927-927e-3629-958f8f211194@huawei.com/T/ > The very first discussion on this was here: > > https://www.spinics.net/lists/dri-devel/msg368077.html > > Please use this link, and not the that one up there you which quoted above, > and whose commit description is taken verbatim from the this link. I found this leaks in bus_register()/class_register()/kset_create_and_add() at first, and describe the reason in these patches which is using kobject_set_name() description, here is the patches:
https://lore.kernel.org/lkml/20221017014957.156645-1-yangyingliang@huawei.com/T/ https://lore.kernel.org/lkml/20221017031335.1845383-1-yangyingliang@huawei.com/ https://lore.kernel.org/lkml/Y0zfPKAgQSrYZg5o@kroah.com/T/
And then I found other subsystem also have this problem, so posted the fix patches for them (including qemu_fw_cfg/f2fs/erofs/ocfs2/amdgpu_discovery):
https://www.mail-archive.com/qemu-devel@nongnu.org/msg915553.html https://lore.kernel.org/linux-f2fs-devel/7908686b-9a7c-b754-d312-d689fc28366e@kernel.org/T/#t https://lore.kernel.org/linux-erofs/20221018073947.693206-1-yangyingliang@huawei.com/ https://lore.kernel.org/lkml/0db486eb-6927-927e-3629-958f8f211194@huawei.com/T/
https://www.spinics.net/lists/dri-devel/msg368092.html In the amdgpu_discovery patch, I sent a old one which using wrong description and you pointer out, and then I send a v2.
And then the maintainer of ocfs2 has different thought about this, so we had a discussion in the link that I gave out, and Greg suggested me to update kset_register() documentation and then put the fix patches together in one series, so I sent this patchset and use the link.
Thanks, Yang
> >> kset_register() is currently used in some places without calling >> kset_put() in error path, because the callers think it should be >> kset internal thing to do, but the driver core can not know what >> caller doing with that memory at times. The memory could be freed >> both in kset_put() and error path of caller, if it is called in >> kset_register(). > As I explained in the link above, the reason there's > a memory leak is that one cannot call kset_register() without > the kset->kobj.name being set--kobj_add_internal() returns -EINVAL, > in this case, i.e. kset_register() fails with -EINVAL. > > Thus, the most common usage is something like this: > > kobj_set_name(&kset->kobj, format, ...); > kset->kobj.kset = parent_kset; > kset->kobj.ktype = ktype; > res = kset_register(kset); > > So, what is being leaked, is the memory allocated in kobj_set_name(), > by the common idiom shown above. This needs to be mentioned in > the documentation, at least, in case, in the future this is absolved > in kset_register() redesign, etc. > > Regards, > Luben > >> So make the function documentation more explicit about calling >> kset_put() in the error path of caller first, so that people >> have a chance to know what to do here, then fixes this leaks >> by calling kset_put() from callers. >> >> Liu Shixin (1): >> ubifs: Fix memory leak in ubifs_sysfs_init() >> >> Yang Yingliang (10): >> kset: fix documentation for kset_register() >> kset: add null pointer check in kset_put() >> bus: fix possible memory leak in bus_register() >> kobject: fix possible memory leak in kset_create_and_add() >> class: fix possible memory leak in __class_register() >> firmware: qemu_fw_cfg: fix possible memory leak in >> fw_cfg_build_symlink() >> f2fs: fix possible memory leak in f2fs_init_sysfs() >> erofs: fix possible memory leak in erofs_init_sysfs() >> ocfs2: possible memory leak in mlog_sys_init() >> drm/amdgpu/discovery: fix possible memory leak >> >> drivers/base/bus.c | 4 +++- >> drivers/base/class.c | 6 ++++++ >> drivers/firmware/qemu_fw_cfg.c | 2 +- >> drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c | 5 +++-- >> fs/erofs/sysfs.c | 4 +++- >> fs/f2fs/sysfs.c | 4 +++- >> fs/ocfs2/cluster/masklog.c | 7 ++++++- >> fs/ubifs/sysfs.c | 2 ++ >> include/linux/kobject.h | 3 ++- >> lib/kobject.c | 5 ++++- >> 10 files changed, 33 insertions(+), 9 deletions(-) >> > .
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