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authorHeiko Carstens <heiko.carstens@de.ibm.com>2011-04-20 10:15:34 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2011-05-02 09:19:43 -0700
commit642dbe81ce8c46e26a190ab641633858961b9ad4 (patch)
tree01d702fa000f4c6a9f93c06cfc3402b8e56e8c65 /arch
parentdb952a764fa4a58b374363878f9eb5aa5525b81f (diff)
downloadlinux-2.6.38-lt-ux500-642dbe81ce8c46e26a190ab641633858961b9ad4.tar.gz
pfault: fix token handling
commit e35c76cd47c244eaa7a74adaabde4d0a1cadb907 upstream. f6649a7e "[S390] cleanup lowcore access from external interrupts" changed handling of external interrupts. Instead of letting the external interrupt handlers accessing the per cpu lowcore the entry code of the kernel reads already all fields that are necessary and passes them to the handlers. The pfault interrupt handler was incorrectly converted. It tries to dereference a value which used to be a pointer to a lowcore field. After the conversion however it is not anymore the pointer to the field but its content. So instead of a dereference only a cast is needed to get the task pointer that caused the pfault. Fixes a NULL pointer dereference and a subsequent kernel crash: Unable to handle kernel pointer dereference at virtual kernel address (null) Oops: 0004 [#1] SMP Modules linked in: nfsd exportfs nfs lockd fscache nfs_acl auth_rpcgss sunrpc loop qeth_l3 qeth vmur ccwgroup ext3 jbd mbcache dm_mod dasd_eckd_mod dasd_diag_mod dasd_mod CPU: 0 Not tainted 2.6.38-2-s390x #1 Process cron (pid: 1106, task: 000000001f962f78, ksp: 000000001fa0f9d0) Krnl PSW : 0404200180000000 000000000002c03e (pfault_interrupt+0xa2/0x138) R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:2 PM:0 EA:3 Krnl GPRS: 0000000000000000 0000000000000001 0000000000000000 0000000000000001 000000001f962f78 0000000000518968 0000000090000002 000000001ff03280 0000000000000000 000000000064f000 000000001f962f78 0000000000002603 0000000006002603 0000000000000000 000000001ff7fe68 000000001ff7fe48 Krnl Code: 000000000002c036: 5820d010 l %r2,16(%r13) 000000000002c03a: 1832 lr %r3,%r2 000000000002c03c: 1a31 ar %r3,%r1 >000000000002c03e: ba23d010 cs %r2,%r3,16(%r13) 000000000002c042: a744fffc brc 4,2c03a 000000000002c046: a7290002 lghi %r2,2 000000000002c04a: e320d0000024 stg %r2,0(%r13) 000000000002c050: 07f0 bcr 15,%r0 Call Trace: ([<000000001f962f78>] 0x1f962f78) [<000000000001acda>] do_extint+0xf6/0x138 [<000000000039b6ca>] ext_no_vtime+0x30/0x34 [<000000007d706e04>] 0x7d706e04 Last Breaking-Event-Address: [<0000000000000000>] 0x0 For stable maintainers: the first kernel which contains this bug is 2.6.37. Reported-by: Stephen Powell <zlinuxman@wowway.com> Cc: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/s390/mm/fault.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 2c57806c085..0f900c811cb 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -558,9 +558,9 @@ static void pfault_interrupt(unsigned int ext_int_code,
* Get the token (= address of the task structure of the affected task).
*/
#ifdef CONFIG_64BIT
- tsk = *(struct task_struct **) param64;
+ tsk = (struct task_struct *) param64;
#else
- tsk = *(struct task_struct **) param32;
+ tsk = (struct task_struct *) param32;
#endif
if (subcode & 0x0080) {