| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.18 176/183] um: Skip futex_atomic_cmpxchg_inatomic() test | Date | Sun, 25 Jan 2015 10:08:18 -0800 |
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3.18-stable review patch. If anyone has any objections, please let me know.
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From: Richard Weinberger <richard@nod.at>
commit f911d731054ab3d82ee72a16b889e17ca3a2332a upstream.
futex_atomic_cmpxchg_inatomic() does not work on UML because it triggers a copy_from_user() in kernel context. On UML copy_from_user() can only be used if the kernel was called by a real user space process such that UML can use ptrace() to fetch the value.
Reported-by: Miklos Szeredi <miklos@szeredi.hu> Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Richard Weinberger <richard@nod.at> Tested-by: Daniel Walter <d.walter@0x90.at> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/um/Kconfig.common | 1 + 1 file changed, 1 insertion(+)
--- a/arch/um/Kconfig.common +++ b/arch/um/Kconfig.common @@ -3,6 +3,7 @@ config UML default y select HAVE_ARCH_AUDITSYSCALL select HAVE_UID16 + select HAVE_FUTEX_CMPXCHG if FUTEX select GENERIC_IRQ_SHOW select GENERIC_CPU_DEVICES select GENERIC_IO
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