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SubjectRe: [PATCH] (please check) Potential security fix for i386/kernel/ptrace.c
On Sun, Sep 20, 1998 at 06:02:47PM -0700, Linus Torvalds wrote:
> Note that it not only ignores the trap, it also clears %db7 if I remember
> correctly, exactly to make sure that the trap doesn't ever happen again.

do_debug tests for vm86 mode before anything else, and handles that as
the first case. %db7 is NOT cleared in this case.

Perhaps a breakpoint can be set in kernel space which triggers while the
user process is in vm86 mode. Should the check for kernel mode trap be
moved earlier?

-- Jamie

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