On a Xen dom0 boot, this feature does not behave, and we end up
calculating:
num_roots = 1
num_nodes = 2
roots_per_node = 0
This causes a divide-by-zero in the modulus inside the loop.
This change adds a couple of guards for invalid states where we might
get a divide-by-zero.
Signed-off-by: Steven Noonan <steven(a)uplinklabs.net>
Signed-off-by: Ariadne Conill <ariadne(a)ariadne.space>
CC: Yazen Ghannam <yazen.ghannam(a)amd.com>
CC: x86(a)vger.kernel.org
CC: stable(a)vger.kernel.org
---
arch/x86/kernel/amd_node.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index 3d0a4768d603c..cdc6ba224d4ad 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -282,6 +282,17 @@ static int __init amd_smn_init(void)
return -ENODEV;
num_nodes = amd_num_nodes();
+
+ if (!num_nodes)
+ return -ENODEV;
+
+ /* Possibly a virtualized environment (e.g. Xen) where we wi
ll get
+ * roots_per_node=0 if the number of roots is fewer than number of
+ * nodes
+ */
+ if (num_roots < num_nodes)
+ return -ENODEV;
+
amd_roots = kcalloc(num_nodes, sizeof(*amd_roots), GFP_KERNEL);
if (!amd_roots)
return -ENOMEM;
--
2.51.2
From: Maciej Wieczor-Retman <maciej.wieczor-retman(a)intel.com>
A KASAN tag mismatch, possibly causing a kernel panic, can be observed
on systems with a tag-based KASAN enabled and with multiple NUMA nodes.
It was reported on arm64 and reproduced on x86. It can be explained in
the following points:
1. There can be more than one virtual memory chunk.
2. Chunk's base address has a tag.
3. The base address points at the first chunk and thus inherits
the tag of the first chunk.
4. The subsequent chunks will be accessed with the tag from the
first chunk.
5. Thus, the subsequent chunks need to have their tag set to
match that of the first chunk.
Use the new vmalloc flag that disables random tag assignment in
__kasan_unpoison_vmalloc() - pass the same random tag to all the
vm_structs by tagging the pointers before they go inside
__kasan_unpoison_vmalloc(). Assigning a common tag resolves the pcpu
chunk address mismatch.
Fixes: 1d96320f8d53 ("kasan, vmalloc: add vmalloc tagging for SW_TAGS")
Cc: stable(a)vger.kernel.org # 6.1+
Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman(a)intel.com>
Reviewed-by: Andrey Konovalov <andreyknvl(a)gmail.com>
---
Changelog v4:
- Add WARN_ON_ONCE() if the new flag is already set in the helper.
(Andrey)
- Remove pr_warn() since the comment should be enough. (Andrey)
Changelog v3:
- Redo the patch by using a flag instead of a new argument in
__kasan_unpoison_vmalloc() (Andrey Konovalov)
Changelog v2:
- Revise the whole patch to match the fixed refactorization from the
first patch.
Changelog v1:
- Rewrite the patch message to point at the user impact of the issue.
- Move helper to common.c so it can be compiled in all KASAN modes.
mm/kasan/common.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 1ed6289d471a..589be3d86735 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -591,11 +591,26 @@ void __kasan_unpoison_vmap_areas(struct vm_struct **vms, int nr_vms,
unsigned long size;
void *addr;
int area;
+ u8 tag;
+
+ /*
+ * If KASAN_VMALLOC_KEEP_TAG was set at this point, all vms[] pointers
+ * would be unpoisoned with the KASAN_TAG_KERNEL which would disable
+ * KASAN checks down the line.
+ */
+ if (WARN_ON_ONCE(flags & KASAN_VMALLOC_KEEP_TAG))
+ return;
+
+ size = vms[0]->size;
+ addr = vms[0]->addr;
+ vms[0]->addr = __kasan_unpoison_vmalloc(addr, size, flags);
+ tag = get_tag(vms[0]->addr);
- for (area = 0 ; area < nr_vms ; area++) {
+ for (area = 1 ; area < nr_vms ; area++) {
size = vms[area]->size;
- addr = vms[area]->addr;
- vms[area]->addr = __kasan_unpoison_vmalloc(addr, size, flags);
+ addr = set_tag(vms[area]->addr, tag);
+ vms[area]->addr =
+ __kasan_unpoison_vmalloc(addr, size, flags | KASAN_VMALLOC_KEEP_TAG);
}
}
#endif
--
2.52.0
From: Maciej Wieczor-Retman <maciej.wieczor-retman(a)intel.com>
A KASAN tag mismatch, possibly causing a kernel panic, can be observed
on systems with a tag-based KASAN enabled and with multiple NUMA nodes.
It was reported on arm64 and reproduced on x86. It can be explained in
the following points:
1. There can be more than one virtual memory chunk.
2. Chunk's base address has a tag.
3. The base address points at the first chunk and thus inherits
the tag of the first chunk.
4. The subsequent chunks will be accessed with the tag from the
first chunk.
5. Thus, the subsequent chunks need to have their tag set to
match that of the first chunk.
Refactor code by reusing __kasan_unpoison_vmalloc in a new helper in
preparation for the actual fix.
Fixes: 1d96320f8d53 ("kasan, vmalloc: add vmalloc tagging for SW_TAGS")
Cc: stable(a)vger.kernel.org # 6.1+
Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman(a)intel.com>
Reviewed-by: Andrey Konovalov <andreyknvl(a)gmail.com>
---
Changelog v1: (after splitting of from the KASAN series)
- Rewrite first paragraph of the patch message to point at the user
impact of the issue.
- Move helper to common.c so it can be compiled in all KASAN modes.
Changelog v2:
- Redo the whole patch so it's an actual refactor.
Changelog v3:
- Redo the patch after applying Andrey's comments to align the code more
with what's already in include/linux/kasan.h
include/linux/kasan.h | 15 +++++++++++++++
mm/kasan/common.c | 17 +++++++++++++++++
mm/vmalloc.c | 4 +---
3 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 6d7972bb390c..cde493cb7702 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -615,6 +615,16 @@ static __always_inline void kasan_poison_vmalloc(const void *start,
__kasan_poison_vmalloc(start, size);
}
+void __kasan_unpoison_vmap_areas(struct vm_struct **vms, int nr_vms,
+ kasan_vmalloc_flags_t flags);
+static __always_inline void
+kasan_unpoison_vmap_areas(struct vm_struct **vms, int nr_vms,
+ kasan_vmalloc_flags_t flags)
+{
+ if (kasan_enabled())
+ __kasan_unpoison_vmap_areas(vms, nr_vms, flags);
+}
+
#else /* CONFIG_KASAN_VMALLOC */
static inline void kasan_populate_early_vm_area_shadow(void *start,
@@ -639,6 +649,11 @@ static inline void *kasan_unpoison_vmalloc(const void *start,
static inline void kasan_poison_vmalloc(const void *start, unsigned long size)
{ }
+static __always_inline void
+kasan_unpoison_vmap_areas(struct vm_struct **vms, int nr_vms,
+ kasan_vmalloc_flags_t flags)
+{ }
+
#endif /* CONFIG_KASAN_VMALLOC */
#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index d4c14359feaf..1ed6289d471a 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -28,6 +28,7 @@
#include <linux/string.h>
#include <linux/types.h>
#include <linux/bug.h>
+#include <linux/vmalloc.h>
#include "kasan.h"
#include "../slab.h"
@@ -582,3 +583,19 @@ bool __kasan_check_byte(const void *address, unsigned long ip)
}
return true;
}
+
+#ifdef CONFIG_KASAN_VMALLOC
+void __kasan_unpoison_vmap_areas(struct vm_struct **vms, int nr_vms,
+ kasan_vmalloc_flags_t flags)
+{
+ unsigned long size;
+ void *addr;
+ int area;
+
+ for (area = 0 ; area < nr_vms ; area++) {
+ size = vms[area]->size;
+ addr = vms[area]->addr;
+ vms[area]->addr = __kasan_unpoison_vmalloc(addr, size, flags);
+ }
+}
+#endif
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 22a73a087135..33e705ccafba 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -4872,9 +4872,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
* With hardware tag-based KASAN, marking is skipped for
* non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc().
*/
- for (area = 0; area < nr_vms; area++)
- vms[area]->addr = kasan_unpoison_vmalloc(vms[area]->addr,
- vms[area]->size, KASAN_VMALLOC_PROT_NORMAL);
+ kasan_unpoison_vmap_areas(vms, nr_vms, KASAN_VMALLOC_PROT_NORMAL);
kfree(vas);
return vms;
--
2.52.0