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authorHeiko Carstens <heiko.carstens@de.ibm.com>2008-03-20 17:33:38 +0100
committerChris Wright <chrisw@sous-sol.org>2008-03-24 11:48:36 -0700
commit78d05881017eef1e9ea49571c52275dc2935e719 (patch)
parent0837aca7b42f1bc9cd8dc1cd4d10aa2aaddaf84d (diff)
S390 futex: let futex_atomic_cmpxchg_pt survive early functional tests.
a0c1e9073ef7428a14309cba010633a6cd6719ea "futex: runtime enable pi and robust functionality" introduces a test wether futex in atomic stuff works or not. It does that by writing to address 0 of the kernel address space. This will crash on older machines where addressing mode switching is enabled but where the mvcos instruction is not available. Page table walking is done by hand and therefore the code tries to access current->mm which is NULL. Therefore add an extra check, so we survive the early test. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Chris Wright <chrisw@sous-sol.org>
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c
index 7e8efaade2ea..5efdfe9f5e76 100644
--- a/arch/s390/lib/uaccess_pt.c
+++ b/arch/s390/lib/uaccess_pt.c
@@ -406,6 +406,8 @@ int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
int ret;
+ if (!current->mm)
+ return -EFAULT;
uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
if (!uaddr) {