s390: fix test_fp_ctl inline assembly contraints

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commit bcf4dd5f9e upstream.

The test_fp_ctl function is used to test if a given value is a valid
floating-point control. The inline assembly in test_fp_ctl uses an
incorrect constraint for the 'orig_fpc' variable. If the compiler
chooses the same register for 'fpc' and 'orig_fpc' the test_fp_ctl()
function always returns true. This allows user space to trigger
kernel oopses with invalid floating-point control values on the
signal stack.

This problem has been introduced with git commit 4725c86055
"s390: fix save and restore of the floating-point-control register"

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

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Martin Schwidefsky 2016-06-27 17:06:45 +02:00 • committed by Ben Hutchings

parent 08015658fb

commit 8955783143

1 changed files with 1 additions and 1 deletions

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arch/s390/include/asm/switch_to.h

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