CVE-2025-39904
PUBLISHED
CVSS 5.5 MEDIUM
In the Linux kernel, the following vulnerability has been resolved:
arm64: kexec: initialize kexec_buf struct in load_other_segments()
Patch series "kexec: Fix invalid field access".
The kexec_buf structure was previously declared without initialization.
commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly")
added a field that is always read but not consistently populated by all
architectures. This un-initialized field will contain garbage.
This is also triggering a UBSAN warning when the uninitialized data was
accessed:
------------[ cut here ]------------
UBSAN: invalid-load in ./include/linux/kexec.h:210:10
load of value 252 is not a valid value for type '_Bool'
Zero-initializing kexec_buf at declaration ensures all fields are cleanly
set, preventing future instances of uninitialized memory being used.
An initial fix was already landed for arm64[0], and this patchset fixes
the problem on the remaining arm64 code and on riscv, as raised by Mark.
Discussions about this problem could be found at[1][2].
This patch (of 3):
The kexec_buf structure was previously declared without initialization.
commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly")
added a field that is always read but not consistently populated by all
architectures. This un-initialized field will contain garbage.
This is also triggering a UBSAN warning when the uninitialized data was
accessed:
------------[ cut here ]------------
UBSAN: invalid-load in ./include/linux/kexec.h:210:10
load of value 252 is not a valid value for type '_Bool'
Zero-initializing kexec_buf at declaration ensures all fields are
cleanly set, preventing future instances of uninitialized memory being
used.
EPSS 0.02% · 4.7th percentile
