adf5054570
Patch series "kunit: fix a UAF bug and do some optimization", v2. This series is to fix UAF (use after free) when running kfence test case test_gfpzero, which is time costly. This UAF bug can be easily triggered by setting CONFIG_KFENCE_NUM_OBJECTS = 65535. Furthermore, some optimization for kunit tests has been done. This patch (of 3): Kunit will create a new thread to run an actual test case, and the main process will wait for the completion of the actual test thread until overtime. The variable "struct kunit test" has local property in function kunit_try_catch_run, and will be used in the test case thread. Task kunit_try_catch_run will free "struct kunit test" when kunit runs overtime, but the actual test case is still run and an UAF bug will be triggered. The above problem has been both observed in a physical machine and qemu platform when running kfence kunit tests. The problem can be triggered when setting CONFIG_KFENCE_NUM_OBJECTS = 65535. Under this setting, the test case test_gfpzero will cost hours and kunit will run to overtime. The follows show the panic log. BUG: unable to handle page fault for address: ffffffff82d882e9 Call Trace: kunit_log_append+0x58/0xd0 ... test_alloc.constprop.0.cold+0x6b/0x8a [kfence_test] test_gfpzero.cold+0x61/0x8ab [kfence_test] kunit_try_run_case+0x4c/0x70 kunit_generic_run_threadfn_adapter+0x11/0x20 kthread+0x166/0x190 ret_from_fork+0x22/0x30 Kernel panic - not syncing: Fatal exception Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 To solve this problem, the test case thread should be stopped when the kunit frame runs overtime. The stop signal will send in function kunit_try_catch_run, and test_gfpzero will handle it. Link: https://lkml.kernel.org/r/20220309083753.1561921-1-liupeng256@huawei.com Link: https://lkml.kernel.org/r/20220309083753.1561921-2-liupeng256@huawei.com Signed-off-by: Peng Liu <liupeng256@huawei.com> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Brendan Higgins <brendanhiggins@google.com> Tested-by: Brendan Higgins <brendanhiggins@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Wang Kefeng <wangkefeng.wang@huawei.com> Cc: Daniel Latypov <dlatypov@google.com> Cc: David Gow <davidgow@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| kernel | ||
| lib | ||
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| samples | ||
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.