diff options
author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2015-08-27 07:12:33 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-09-02 07:05:46 +0200 |
commit | f5b150b99bf0aa09e0fabc36e599cae14eb5b66c (patch) | |
tree | 8eac4c200c91498336c4f0e1e58509ca605fa8dc | |
parent | f2888dd24d315db4fc35cc610eb205d387904e69 (diff) |
arm64: flush FP/SIMD state correctly after execve()
commit 674c242c9323d3c293fc4f9a3a3a619fe3063290 upstream.
When a task calls execve(), its FP/SIMD state is flushed so that
none of the original program state is observeable by the incoming
program.
However, since this flushing consists of setting the in-memory copy
of the FP/SIMD state to all zeroes, the CPU field is set to CPU 0 as
well, which indicates to the lazy FP/SIMD preserve/restore code that
the FP/SIMD state does not need to be reread from memory if the task
is scheduled again on CPU 0 without any other tasks having entered
userland (or used the FP/SIMD in kernel mode) on the same CPU in the
mean time. If this happens, the FP/SIMD state of the old program will
still be present in the registers when the new program starts.
So set the CPU field to the invalid value of NR_CPUS when performing
the flush, by calling fpsimd_flush_task_state().
Reported-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Reported-by: Janet Liu <janet.liu@spreadtrum.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | arch/arm64/kernel/fpsimd.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 3dca15634e69..c31e59fe2cb8 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -157,6 +157,7 @@ void fpsimd_thread_switch(struct task_struct *next) void fpsimd_flush_thread(void) { memset(¤t->thread.fpsimd_state, 0, sizeof(struct fpsimd_state)); + fpsimd_flush_task_state(current); set_thread_flag(TIF_FOREIGN_FPSTATE); } |