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Patch series "liveupdate: fixes in error handling".
This series contains some fixes in LUO's error handling paths.
The first patch deals with failed freeze() attempts. The cleanup path
calls unfreeze, and that clears some data needed by later unpreserve
calls.
The second patch is a bit more involved. It deals with failed retrieve()
attempts. To do so properly, it reworks some of the error handling logic
in luo_file core.
Both these fixes are "theoretical" -- in the sense that I have not been
able to reproduce either of them in normal operation. The only supported
file type right now is memfd, and there is nothing userspace can do right
now to make it fail its retrieve or freeze. I need to make the retrieve
or freeze fail by artificially injecting errors. The injected errors
trigger a use-after-free and a double-free.
That said, once more complex file handlers are added or memfd preservation
is used in ways not currently expected or covered by the tests, we will be
able to see them on real systems.
This patch (of 2):
The unfreeze operation is supposed to undo the effects of the freeze
operation. serialized_data is not set by freeze, but by preserve.
Consequently, the unpreserve operation needs to access serialized_data to
undo the effects of the preserve operation. This includes freeing the
serialized data structures for example.
If a freeze callback fails, unfreeze is called for all frozen files. This
would clear serialized_data for them. Since live update has failed, it
can be expected that userspace aborts, releasing all sessions. When the
sessions are released, unpreserve will be called for all files. The
unfrozen files will see 0 in their serialized_data. This is not expected
by file handlers, and they might either fail, leaking data and state, or
might even crash or cause invalid memory access.
Do not clear serialized_data on unfreeze so it gets passed on to
unpreserve. There is no need to clear it on unpreserve since luo_file
will be freed immediately after.
Link: https://lkml.kernel.org/r/20260126230302.2936817-1-pratyush@kernel.org
Link: https://lkml.kernel.org/r/20260126230302.2936817-2-pratyush@kernel.org
Fixes: 7c722a7f44e0 ("liveupdate: luo_file: implement file systems callbacks")
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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If we exit a list_for_each_entry() without hitting a break then the list
iterator points to an offset from the list_head. It's a non-NULL but
invalid pointer and dereferencing it isn't allowed.
Introduce a new "found" variable to test instead.
Link: https://lkml.kernel.org/r/aSlMc4SS09Re4_xn@stanley.mountain
Fixes: 3ee1d673194e ("liveupdate: luo_file: implement file systems callbacks")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/r/202511280420.y9O4fyhX-lkp@intel.com/
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Currently file handlers only get the serialized_data field to store their
state. This field has a pointer to the serialized state of the file, and
it becomes a part of LUO file's serialized state.
File handlers can also need some runtime state to track information that
shouldn't make it in the serialized data.
One such example is a vmalloc pointer. While kho_preserve_vmalloc()
preserves the memory backing a vmalloc allocation, it does not store the
original vmap pointer, since that has no use being passed to the next
kernel. The pointer is needed to free the memory in case the file is
unpreserved.
Provide a private field in struct luo_file and pass it to all the
callbacks. The field's can be set by preserve, and must be freed by
unpreserve.
Link: https://lkml.kernel.org/r/20251125165850.3389713-14-pasha.tatashin@soleen.com
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
Co-developed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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This patch implements the core mechanism for managing preserved files
throughout the live update lifecycle. It provides the logic to invoke the
file handler callbacks (preserve, unpreserve, freeze, unfreeze, retrieve,
and finish) at the appropriate stages.
During the reboot phase, luo_file_freeze() serializes the final metadata
for each file (handler compatible string, token, and data handle) into a
memory region preserved by KHO. In the new kernel, luo_file_deserialize()
reconstructs the in-memory file list from this data, preparing the session
for retrieval.
Link: https://lkml.kernel.org/r/20251125165850.3389713-7-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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