Bug 2495933 (CVE-2026-53343) - CVE-2026-53343 kernel: ARM: 9475/1: entry: use byte load for KASAN VMAP stack shadow
Summary: CVE-2026-53343 kernel: ARM: 9475/1: entry: use byte load for KASAN VMAP stack...
Keywords:
Status: NEW
Alias: CVE-2026-53343
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
unspecified
unspecified
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-01 14:01 UTC by OSIDB Bzimport
Modified: 2026-07-01 18:50 UTC (History)
2 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-07-01 14:01:53 UTC
In the Linux kernel, the following vulnerability has been resolved:

ARM: 9475/1: entry: use byte load for KASAN VMAP stack shadow

Commit 44e9a3bb76e5 ("ARM: 9430/1: entry: Do a dummy read from
VMAP shadow") added a dummy read from the KASAN VMAP stack shadow in
__switch_to(). The read uses ldr, but the KASAN shadow address is
byte-granular and is not guaranteed to be word aligned.

ARMv5 faults unaligned word loads. With CONFIG_KASAN_VMALLOC and
CONFIG_VMAP_STACK enabled, ARM926/VersatilePB crashes in __switch_to()
with an alignment exception before reaching init.

Use ldrb for the dummy shadow access. The code only needs to fault in the
shadow mapping if the stack shadow is missing, so a byte load is sufficient
and matches the granularity of KASAN shadow memory.

Comment 1 Mauro Matteo Cascella 2026-07-01 18:42:43 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026070144-CVE-2026-53343-e76a@gregkh/T


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