Commit b3dcf3de authored Oct 29, 2009 by Heiko Carstens Committed by Martin Schwidefsky Oct 29, 2009

[S390] smp: fix sigp sense handling



sigp sense only returns the status of a cpu if it is non zero. If the
status of the sensed cpu is all zeros condition code 0 (accpeted) is
set and no status bits are returned.
The current code however assumes that a status was returned and tests
bits in it. This means uninitalized data is accessed with random
results.
Worst case is that the code that checks if cpu is offline on cpu
hotplug assumes that the target cpu is offline while it is still
running. This leads potentially to memory corruption since resources
that are still needed by the target cpu will be freed and could be
resused while still in use.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent f8501ba7

arch/s390/kernel/smp.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -76,7 +76,6 @@ static int cpu_stopped(int cpu)
		__u32 status;

		switch (signal_processor_ps(&status, 0, cpu, sigp_sense)) {
		case sigp_order_code_accepted:
		case sigp_status_stored:
		/* Check for stopped and check stop state */
		if (status & 0x50)

arch/s390/kernel/swsusp_asm64.S

+1 −0

Original line number	Diff line number	Diff line
		@@ -207,6 +207,7 @@ restart_suspend:
		llgh %r2,0(%r1)
		7:
		sigp %r9,%r2,__SIGP_SENSE /* Wait for resume CPU */
		brc 8,7b /* accepted, status 0, still running */
		brc 2,7b /* busy, try again */
		tmll %r9,0x40 /* Test if resume CPU is stopped */
		jz 7b

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