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Out-of-bounds accesses that aren't caught by a guard page will result in corruption of canary memory. In pathological cases, where an object has certain alignment requirements, an out-of-bounds access might never be caught by the guard page. Such corruptions, however, are only detected on kfree() normally. If the bug causes the kernel to panic before kfree(), KFENCE has no opportunity to report the issue. Such corruptions may also indicate failing memory or other faults. To provide some more information in such cases, add the option to check canary bytes on panic. This might help narrow the search for the panic cause; but, due to only having the allocation stack trace, such reports are difficult to use to diagnose an issue alone. In most cases, such reports are inactionable, and is therefore an opt-in feature (disabled by default). [akpm@linux-foundation.org: add __read_mostly, per Marco] Link: https://lkml.kernel.org/r/20220425022456.44300-1-huangshaobo6@huawei.com Signed-off-by: huangshaobo <huangshaobo6@huawei.com> Suggested-by: chenzefeng <chenzefeng2@huawei.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Xiaoming Ni <nixiaoming@huawei.com> Cc: Wangbing <wangbing6@huawei.com> Cc: Jubin Zhong <zhongjubin@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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| core.c | ||
| kfence_test.c | ||
| kfence.h | ||
| Makefile | ||
| report.c | ||