x86, vsyscall: fix the oops crash with __pa_vsymbol()

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Appended patch fixes an oops while changing the vsyscall sysctl.
I am sure no one tested this code before integrating into mainline :(

BTW, using ioremap() in vsyscall_sysctl_change() to get the virtual
address of a kernel symbol sounds like an over kill.. I wonder if we
can define a simple __va_vsymbol() which will return directly the
kernel direct mapping. comments in the code which says gcc has trouble
with __va(__pa()) sounds bogus to me. __pa() on a vsyscall address will
not work anyhow :(

And also, the whole nop out syscall in vsyscall page infrastructure
(vsyscall_sysctl_change()) is added to make some attacks difficult,
and yet I don't see this nop out being done by default. This area
requires more cleanups?

Fix an oops with __pa_vsymbol(). VSYSCALL_FIRST_PAGE is a fixmap index.
We want the starting virtual address of the vsyscall page and not the index.

[ mingo: arch/x86 adaptation ]

Reported-by: Yanmin Zhang <yanmin.zhang@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

...

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Siddha, Suresh B 2007-10-19 20:35:02 +02:00 • committed by Thomas Gleixner

parent f322727b92

commit 957ff882f9

1 changed files with 1 additions and 1 deletions

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arch/x86/kernel/vsyscall_64.c

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