[S390] CVE-2008-1514: prevent ptrace padding area read/write in 31-bit mode
When running a 31-bit ptrace, on either an s390 or s390x kernel,
reads and writes into a padding area in struct user_regs_struct32
will result in a kernel panic.
This is also known as CVE-2008-1514.
Test case available here:
http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/user-area-padding.c?cvsroot=systemtap
Steps to reproduce:
1) wget the above
2) gcc -o user-area-padding-31bit user-area-padding.c -Wall -ggdb2 -D_GNU_SOURCE -m31
3) ./user-area-padding-31bit
<panic>
Test status
-----------
Without patch, both s390 and s390x kernels panic. With patch, the test case,
as well as the gdb testsuite, pass without incident, padding area reads
returning zero, writes ignored.
Nb: original version returned -EINVAL on write attempts, which broke the
gdb test and made the test case slightly unhappy, Jan Kratochvil suggested
the change to return 0 on write attempts.
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Tested-by: Jan Kratochvil <jan.kratochvil@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/compat_ptrace.h b/arch/s390/kernel/compat_ptrace.h
index cde81fa..a2be3a9 100644
--- a/arch/s390/kernel/compat_ptrace.h
+++ b/arch/s390/kernel/compat_ptrace.h
@@ -42,6 +42,7 @@
u32 gprs[NUM_GPRS];
u32 acrs[NUM_ACRS];
u32 orig_gpr2;
+ /* nb: there's a 4-byte hole here */
s390_fp_regs fp_regs;
/*
* These per registers are in here so that gdb can modify them