From: Benjamin Berg <benjamin.berg@xxxxxxxxx> On the x86 and um architectures struct task_struct is dynamically sized depending on the size required to store the floating point registers. After adding this feature to UML it sometimes triggered KASAN errors as the memcpy in arch_dup_task_struct read past init_task. In my own testing, the reported KASAN error was for a read into the redzone of the next global variable (init_sighand). Due to padding, the reported area was already far past the size of init_task. Note that on x86 the dynamically allocated area of struct task_struct is quite a bit smaller and may not even exist. This might explain why this error has not been noticed before. This problem was reported by Brian Norris <briannorris@xxxxxxxxxxxx>. Benjamin Benjamin Berg (3): vmlinux.lds.h: remove entry to place init_task onto init_stack um: avoid copying FP state from init_task x86: avoid copying dynamic FP state from init_task arch/um/kernel/process.c | 10 +++++++++- arch/x86/kernel/process.c | 10 +++++++++- include/asm-generic/vmlinux.lds.h | 1 - 3 files changed, 18 insertions(+), 3 deletions(-) -- 2.47.1
