This is a note to let you know that I've just added the patch titled arm64: flush FP/SIMD state correctly after execve() to the 4.2-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm64-flush-fp-simd-state-correctly-after-execve.patch and it can be found in the queue-4.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 674c242c9323d3c293fc4f9a3a3a619fe3063290 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Date: Thu, 27 Aug 2015 07:12:33 +0100 Subject: arm64: flush FP/SIMD state correctly after execve() From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> 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@xxxxxxxxxxxxxx> Reported-by: Janet Liu <janet.liu@xxxxxxxxxxxxxx> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Signed-off-by: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/kernel/fpsimd.c | 1 + 1 file changed, 1 insertion(+) --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -158,6 +158,7 @@ void fpsimd_thread_switch(struct task_st 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); } Patches currently in stable-queue which might be from ard.biesheuvel@xxxxxxxxxx are queue-4.2/arm64-set-max_memblock_addr-according-to-linear-region-size.patch queue-4.2/arm64-flush-fp-simd-state-correctly-after-execve.patch queue-4.2/of-fdt-make-memblock-maximum-physical-address-arch-configurable.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html