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.
Unpoison all vm_structs after allocating them for the percpu allocator.
Use the same tag to resolve 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>
Tested-by: Baoquan He <bhe(a)redhat.com>
---
Changelog v1 (after splitting of from the KASAN series):
- 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 | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index c63544a98c24..a6bbc68984cd 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -584,12 +584,20 @@ bool __kasan_check_byte(const void *address, unsigned long ip)
return true;
}
+/*
+ * A tag mismatch happens when calculating per-cpu chunk addresses, because
+ * they all inherit the tag from vms[0]->addr, even when nr_vms is bigger
+ * than 1. This is a problem because all the vms[]->addr come from separate
+ * allocations and have different tags so while the calculated address is
+ * correct the tag isn't.
+ */
void __kasan_unpoison_vmap_areas(struct vm_struct **vms, int nr_vms)
{
int area;
for (area = 0 ; area < nr_vms ; area++) {
kasan_poison(vms[area]->addr, vms[area]->size,
- arch_kasan_get_tag(vms[area]->addr), false);
+ arch_kasan_get_tag(vms[0]->addr), false);
+ arch_kasan_set_tag(vms[area]->addr, arch_kasan_get_tag(vms[0]->addr));
}
}
--
2.51.0
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From: Owen Gu <guhuinan(a)xiaomi.com>
[ Upstream commit cfd6f1a7b42f ("usb: gadget: f_fs: Fix epfile null
pointer access after ep enable.") ]
A race condition occurs when ffs_func_eps_enable() runs concurrently
with ffs_data_reset(). The ffs_data_clear() called in ffs_data_reset()
sets ffs->epfiles to NULL before resetting ffs->eps_count to 0, leading
to a NULL pointer dereference when accessing epfile->ep in
ffs_func_eps_enable() after successful usb_ep_enable().
The ffs->epfiles pointer is set to NULL in both ffs_data_clear() and
ffs_data_close() functions, and its modification is protected by the
spinlock ffs->eps_lock. And the whole ffs_func_eps_enable() function
is also protected by ffs->eps_lock.
Thus, add NULL pointer handling for ffs->epfiles in the
ffs_func_eps_enable() function to fix issues
Signed-off-by: Owen Gu <guhuinan(a)xiaomi.com>
Link: https://lore.kernel.org/r/20250915092907.17802-1-guhuinan@xiaomi.com
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
drivers/usb/gadget/function/f_fs.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 08a251df20c4..04058261cdd0 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -2407,7 +2407,12 @@ static int ffs_func_eps_enable(struct ffs_function *func)
ep = func->eps;
epfile = ffs->epfiles;
count = ffs->eps_count;
- while(count--) {
+ if (!epfile) {
+ ret = -ENOMEM;
+ goto done;
+ }
+
+ while (count--) {
ep->ep->driver_data = ep;
ret = config_ep_by_speed(func->gadget, &func->function, ep->ep);
@@ -2431,6 +2436,7 @@ static int ffs_func_eps_enable(struct ffs_function *func)
}
wake_up_interruptible(&ffs->wait);
+done:
spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
return ret;
--
2.43.0
The quilt patch titled
Subject: kasan: unpoison vms[area] addresses with a common tag
has been removed from the -mm tree. Its filename was
kasan-unpoison-vms-addresses-with-a-common-tag.patch
This patch was dropped because an updated version will be issued
------------------------------------------------------
From: Maciej Wieczor-Retman <maciej.wieczor-retman(a)intel.com>
Subject: kasan: unpoison vms[area] addresses with a common tag
Date: Tue, 04 Nov 2025 14:49:48 +0000
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.
Unpoison all vm_structs after allocating them for the percpu allocator.
Use the same tag to resolve the pcpu chunk address mismatch.
Link: https://lkml.kernel.org/r/cf8fe0ffcdbf54e06d9df26c8473b123c4065f02.17622670…
Fixes: 1d96320f8d53 ("kasan, vmalloc: add vmalloc tagging for SW_TAGS")
Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman(a)intel.com>
Tested-by: Baoquan He <bhe(a)redhat.com>
Cc: Alexander Potapenko <glider(a)google.com>
Cc: Andrey Konovalov <andreyknvl(a)gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a(a)gmail.com>
Cc: Dmitriy Vyukov <dvyukov(a)google.com>
Cc: Marco Elver <elver(a)google.com>
Cc: "Uladzislau Rezki (Sony)" <urezki(a)gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino(a)arm.com>
Cc: <stable(a)vger.kernel.org> [6.1+]
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/kasan/common.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/mm/kasan/common.c~kasan-unpoison-vms-addresses-with-a-common-tag
+++ a/mm/kasan/common.c
@@ -584,12 +584,20 @@ bool __kasan_check_byte(const void *addr
return true;
}
+/*
+ * A tag mismatch happens when calculating per-cpu chunk addresses, because
+ * they all inherit the tag from vms[0]->addr, even when nr_vms is bigger
+ * than 1. This is a problem because all the vms[]->addr come from separate
+ * allocations and have different tags so while the calculated address is
+ * correct the tag isn't.
+ */
void __kasan_unpoison_vmap_areas(struct vm_struct **vms, int nr_vms)
{
int area;
for (area = 0 ; area < nr_vms ; area++) {
kasan_poison(vms[area]->addr, vms[area]->size,
- arch_kasan_get_tag(vms[area]->addr), false);
+ arch_kasan_get_tag(vms[0]->addr), false);
+ arch_kasan_set_tag(vms[area]->addr, arch_kasan_get_tag(vms[0]->addr));
}
}
_
Patches currently in -mm which might be from maciej.wieczor-retman(a)intel.com are