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    Subject[PATCH 4.14 295/315] x86/fpu: Limit xstate copy size in xstateregs_set()
    Date
    From: Thomas Gleixner <tglx@linutronix.de>

    [ Upstream commit 07d6688b22e09be465652cf2da0da6bf86154df6 ]

    If the count argument is larger than the xstate size, this will happily
    copy beyond the end of xstate.

    Fixes: 91c3dba7dbc1 ("x86/fpu/xstate: Fix PTRACE frames for XSAVES")
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    Reviewed-by: Andy Lutomirski <luto@kernel.org>
    Reviewed-by: Borislav Petkov <bp@suse.de>
    Link: https://lkml.kernel.org/r/20210623121452.120741557@linutronix.de
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/kernel/fpu/regset.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
    index bc02f5144b95..621d249ded0b 100644
    --- a/arch/x86/kernel/fpu/regset.c
    +++ b/arch/x86/kernel/fpu/regset.c
    @@ -128,7 +128,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
    /*
    * A whole standard-format XSAVE buffer is needed:
    */
    - if ((pos != 0) || (count < fpu_user_xstate_size))
    + if (pos != 0 || count != fpu_user_xstate_size)
    return -EFAULT;

    xsave = &fpu->state.xsave;
    --
    2.30.2


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