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Message-ID: <20240806071616.1671691-1-ruanjinjie@huawei.com>
Date: Tue, 6 Aug 2024 07:16:16 +0000
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <dennis@...nel.org>, <tj@...nel.org>, <cl@...ux.com>,
<mpe@...erman.id.au>, <benh@...nel.crashing.org>, <paulus@...ba.org>,
<christophe.leroy@...roup.eu>, <mahesh@...ux.ibm.com>,
<gregkh@...uxfoundation.org>, <linuxppc-dev@...ts.ozlabs.org>,
<linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>
CC: <ruanjinjie@...wei.com>
Subject: [PATCH v5.10 v2] powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.
From: Mahesh Salgaonkar <mahesh@...ux.ibm.com>
[ Upstream commit 0db880fc865ffb522141ced4bfa66c12ab1fbb70 ]
nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel
crash when invoked during real mode interrupt handling (e.g. early HMI/MCE
interrupt handler) if percpu allocation comes from vmalloc area.
Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI()
wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when
percpu allocation is from the embedded first chunk. However with
CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu
allocation can come from the vmalloc area.
With kernel command line "percpu_alloc=page" we can force percpu allocation
to come from vmalloc area and can see kernel crash in machine_check_early:
[ 1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110
[ 1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0
[ 1.215719] --- interrupt: 200
[ 1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable)
[ 1.215722] [c000000fffd731b0] [0000000000000000] 0x0
[ 1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8
Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu
first chunk is not embedded.
CVE-2024-42126
Cc: stable@...r.kernel.org#5.10.x
Cc: gregkh@...uxfoundation.org
Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>
Tested-by: Shirisha Ganta <shirisha@...ux.ibm.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@...ux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://msgid.link/20240410043006.81577-1-mahesh@linux.ibm.com
[ Conflicts in arch/powerpc/include/asm/interrupt.h
because machine_check_early() and machine_check_exception()
has been refactored. ]
Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
v2:
- Also fix for CONFIG_PPC_BOOK3S_64 not enabled.
- Add Upstream.
- Cc stable@...r.kernel.org.
---
arch/powerpc/include/asm/percpu.h | 10 ++++++++++
arch/powerpc/kernel/mce.c | 14 +++++++++++---
arch/powerpc/kernel/setup_64.c | 2 ++
arch/powerpc/kernel/traps.c | 8 +++++++-
4 files changed, 30 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/percpu.h b/arch/powerpc/include/asm/percpu.h
index 8e5b7d0b851c..634970ce13c6 100644
--- a/arch/powerpc/include/asm/percpu.h
+++ b/arch/powerpc/include/asm/percpu.h
@@ -15,6 +15,16 @@
#endif /* CONFIG_SMP */
#endif /* __powerpc64__ */
+#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) && defined(CONFIG_SMP)
+#include <linux/jump_label.h>
+DECLARE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged);
+
+#define percpu_first_chunk_is_paged \
+ (static_key_enabled(&__percpu_first_chunk_is_paged.key))
+#else
+#define percpu_first_chunk_is_paged false
+#endif /* CONFIG_PPC64 && CONFIG_SMP */
+
#include <asm-generic/percpu.h>
#include <asm/paca.h>
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index 63702c0badb9..259343040e1b 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -594,8 +594,15 @@ long notrace machine_check_early(struct pt_regs *regs)
u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
this_cpu_set_ftrace_enabled(0);
- /* Do not use nmi_enter/exit for pseries hpte guest */
- if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
+ /*
+ * Do not use nmi_enter/exit for pseries hpte guest
+ *
+ * Likewise, do not use it in real mode if percpu first chunk is not
+ * embedded. With CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there
+ * are chances where percpu allocation can come from vmalloc area.
+ */
+ if ((radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR)) &&
+ !percpu_first_chunk_is_paged)
nmi_enter();
hv_nmi_check_nonrecoverable(regs);
@@ -606,7 +613,8 @@ long notrace machine_check_early(struct pt_regs *regs)
if (ppc_md.machine_check_early)
handled = ppc_md.machine_check_early(regs);
- if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
+ if ((radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR)) &&
+ !percpu_first_chunk_is_paged)
nmi_exit();
this_cpu_set_ftrace_enabled(ftrace_enabled);
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 3f8426bccd16..899d87de0165 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -824,6 +824,7 @@ static int pcpu_cpu_distance(unsigned int from, unsigned int to)
unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(__per_cpu_offset);
+DEFINE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged);
static void __init pcpu_populate_pte(unsigned long addr)
{
@@ -903,6 +904,7 @@ void __init setup_per_cpu_areas(void)
if (rc < 0)
panic("cannot initialize percpu area (err=%d)", rc);
+ static_key_enable(&__percpu_first_chunk_is_paged.key);
delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
for_each_possible_cpu(cpu) {
__per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index b0e87dce2b9a..b4d108bef814 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -835,8 +835,14 @@ void machine_check_exception(struct pt_regs *regs)
* This is silly. The BOOK3S_64 should just call a different function
* rather than expecting semantics to magically change. Something
* like 'non_nmi_machine_check_exception()', perhaps?
+ *
+ * Do not use nmi_enter/exit in real mode if percpu first chunk is
+ * not embedded. With CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled
+ * there are chances where percpu allocation can come from
+ * vmalloc area.
*/
- const bool nmi = !IS_ENABLED(CONFIG_PPC_BOOK3S_64);
+ const bool nmi = !IS_ENABLED(CONFIG_PPC_BOOK3S_64) &&
+ !percpu_first_chunk_is_paged;
if (nmi) nmi_enter();
--
2.34.1
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