* [PATCH v2 for-4.4-stable] s390/smp: Fix calling smp_call_ipl_cpu() from ipl CPU [not found] <154875549211637@kroah.com> @ 2019-01-30 15:21 ` David Hildenbrand 2019-01-31 7:54 ` Greg KH 0 siblings, 1 reply; 2+ messages in thread From: David Hildenbrand @ 2019-01-30 15:21 UTC (permalink / raw) To: stable; +Cc: gregkh, cohuck, schwidefsky, David Hildenbrand commit 60f1bf29c0b2519989927cae640cd1f50f59dc7f upstream. When calling smp_call_ipl_cpu() from the IPL CPU, we will try to read from pcpu_devices->lowcore. However, due to prefixing, that will result in reading from absolute address 0 on that CPU. We have to go via the actual lowcore instead. This means that right now, we will read lc->nodat_stack == 0 and therfore work on a very wrong stack. This BUG essentially broke rebooting under QEMU TCG (which will report a low address protection exception). And checking under KVM, it is also broken under KVM. With 1 VCPU it can be easily triggered. :/# echo 1 > /proc/sys/kernel/sysrq :/# echo b > /proc/sysrq-trigger [ 28.476745] sysrq: SysRq : Resetting [ 28.476793] Kernel stack overflow. [ 28.476817] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13 [ 28.476820] Hardware name: IBM 2964 NE1 716 (KVM/Linux) [ 28.476826] Krnl PSW : 0400c00180000000 0000000000115c0c (pcpu_delegate+0x12c/0x140) [ 28.476861] R:0 T:1 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 [ 28.476863] Krnl GPRS: ffffffffffffffff 0000000000000000 000000000010dff8 0000000000000000 [ 28.476864] 0000000000000000 0000000000000000 0000000000ab7090 000003e0006efbf0 [ 28.476864] 000000000010dff8 0000000000000000 0000000000000000 0000000000000000 [ 28.476865] 000000007fffc000 0000000000730408 000003e0006efc58 0000000000000000 [ 28.476887] Krnl Code: 0000000000115bfe: 4170f000 la %r7,0(%r15) [ 28.476887] 0000000000115c02: 41f0a000 la %r15,0(%r10) [ 28.476887] #0000000000115c06: e370f0980024 stg %r7,152(%r15) [ 28.476887] >0000000000115c0c: c0e5fffff86e brasl %r14,114ce8 [ 28.476887] 0000000000115c12: 41f07000 la %r15,0(%r7) [ 28.476887] 0000000000115c16: a7f4ffa8 brc 15,115b66 [ 28.476887] 0000000000115c1a: 0707 bcr 0,%r7 [ 28.476887] 0000000000115c1c: 0707 bcr 0,%r7 [ 28.476901] Call Trace: [ 28.476902] Last Breaking-Event-Address: [ 28.476920] [<0000000000a01c4a>] arch_call_rest_init+0x22/0x80 [ 28.476927] Kernel panic - not syncing: Corrupt kernel stack, can't continue. [ 28.476930] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13 [ 28.476932] Hardware name: IBM 2964 NE1 716 (KVM/Linux) [ 28.476932] Call Trace: Fixes: 2f859d0dad81 ("s390/smp: reduce size of struct pcpu") Cc: stable@vger.kernel.org # 4.0+ Reported-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> --- arch/s390/kernel/smp.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 77f4f334a465..f5bfd9d95da1 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -360,9 +360,13 @@ void smp_call_online_cpu(void (*func)(void *), void *data) */ void smp_call_ipl_cpu(void (*func)(void *), void *data) { + struct _lowcore *lc = pcpu_devices->lowcore; + + if (pcpu_devices[0].address == stap()) + lc = &S390_lowcore; + pcpu_delegate(&pcpu_devices[0], func, data, - pcpu_devices->lowcore->panic_stack - - PANIC_FRAME_OFFSET + PAGE_SIZE); + lc->panic_stack - PANIC_FRAME_OFFSET + PAGE_SIZE); } int smp_find_processor_id(u16 address) -- 2.17.2 ^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2 for-4.4-stable] s390/smp: Fix calling smp_call_ipl_cpu() from ipl CPU 2019-01-30 15:21 ` [PATCH v2 for-4.4-stable] s390/smp: Fix calling smp_call_ipl_cpu() from ipl CPU David Hildenbrand @ 2019-01-31 7:54 ` Greg KH 0 siblings, 0 replies; 2+ messages in thread From: Greg KH @ 2019-01-31 7:54 UTC (permalink / raw) To: David Hildenbrand; +Cc: stable, cohuck, schwidefsky On Wed, Jan 30, 2019 at 04:21:07PM +0100, David Hildenbrand wrote: > commit 60f1bf29c0b2519989927cae640cd1f50f59dc7f upstream. > > When calling smp_call_ipl_cpu() from the IPL CPU, we will try to read > from pcpu_devices->lowcore. However, due to prefixing, that will result > in reading from absolute address 0 on that CPU. We have to go via the > actual lowcore instead. > > This means that right now, we will read lc->nodat_stack == 0 and > therfore work on a very wrong stack. > > This BUG essentially broke rebooting under QEMU TCG (which will report > a low address protection exception). And checking under KVM, it is > also broken under KVM. With 1 VCPU it can be easily triggered. > > :/# echo 1 > /proc/sys/kernel/sysrq > :/# echo b > /proc/sysrq-trigger > [ 28.476745] sysrq: SysRq : Resetting > [ 28.476793] Kernel stack overflow. > [ 28.476817] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13 > [ 28.476820] Hardware name: IBM 2964 NE1 716 (KVM/Linux) > [ 28.476826] Krnl PSW : 0400c00180000000 0000000000115c0c (pcpu_delegate+0x12c/0x140) > [ 28.476861] R:0 T:1 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 > [ 28.476863] Krnl GPRS: ffffffffffffffff 0000000000000000 000000000010dff8 0000000000000000 > [ 28.476864] 0000000000000000 0000000000000000 0000000000ab7090 000003e0006efbf0 > [ 28.476864] 000000000010dff8 0000000000000000 0000000000000000 0000000000000000 > [ 28.476865] 000000007fffc000 0000000000730408 000003e0006efc58 0000000000000000 > [ 28.476887] Krnl Code: 0000000000115bfe: 4170f000 la %r7,0(%r15) > [ 28.476887] 0000000000115c02: 41f0a000 la %r15,0(%r10) > [ 28.476887] #0000000000115c06: e370f0980024 stg %r7,152(%r15) > [ 28.476887] >0000000000115c0c: c0e5fffff86e brasl %r14,114ce8 > [ 28.476887] 0000000000115c12: 41f07000 la %r15,0(%r7) > [ 28.476887] 0000000000115c16: a7f4ffa8 brc 15,115b66 > [ 28.476887] 0000000000115c1a: 0707 bcr 0,%r7 > [ 28.476887] 0000000000115c1c: 0707 bcr 0,%r7 > [ 28.476901] Call Trace: > [ 28.476902] Last Breaking-Event-Address: > [ 28.476920] [<0000000000a01c4a>] arch_call_rest_init+0x22/0x80 > [ 28.476927] Kernel panic - not syncing: Corrupt kernel stack, can't continue. > [ 28.476930] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13 > [ 28.476932] Hardware name: IBM 2964 NE1 716 (KVM/Linux) > [ 28.476932] Call Trace: > > Fixes: 2f859d0dad81 ("s390/smp: reduce size of struct pcpu") > Cc: stable@vger.kernel.org # 4.0+ > Reported-by: Cornelia Huck <cohuck@redhat.com> > Signed-off-by: David Hildenbrand <david@redhat.com> > Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> > --- > arch/s390/kernel/smp.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) Now queued up, thanks. greg k-h ^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-01-30 15:21 ` [PATCH v2 for-4.4-stable] s390/smp: Fix calling smp_call_ipl_cpu() from ipl CPU David Hildenbrand
2019-01-31 7:54 ` Greg KH
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