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author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2015-08-27 07:12:33 +0100 |
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committer | Will Deacon <will.deacon@arm.com> | 2015-08-27 09:55:26 +0100 |
commit | 674c242c9323d3c293fc4f9a3a3a619fe3063290 (patch) | |
tree | d57a5528cbc4c6362ba74bec58ce7d7f88ffbb81 /arch/arm64/kernel/fpsimd.c | |
parent | 5166c20ef95be89d10ffe0140e74df5cf26e9786 (diff) | |
download | linux-stable-674c242c9323d3c293fc4f9a3a3a619fe3063290.tar.gz linux-stable-674c242c9323d3c293fc4f9a3a3a619fe3063290.tar.bz2 linux-stable-674c242c9323d3c293fc4f9a3a3a619fe3063290.zip |
arm64: flush FP/SIMD state correctly after execve()
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().
Cc: <stable@vger.kernel.org>
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>
Diffstat (limited to 'arch/arm64/kernel/fpsimd.c')
-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 44d6f7545505..c56956a16d3f 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -158,6 +158,7 @@ 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); } |