diff options
| author | Michael Zhivich <mzhivich@akamai.com> | 2025-07-23 09:40:19 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-08-01 09:48:44 +0100 |
| commit | 3ad50c7c66cc2bd6e09f4601b6a115f4f77d33d9 (patch) | |
| tree | 1eec24d2daca668af422418b63d1753a8833e2aa | |
| parent | b85815675fc5a175c2499ca35c4641f1924d5ad5 (diff) | |
x86/bugs: Fix use of possibly uninit value in amd_check_tsa_microcode()
For kernels compiled with CONFIG_INIT_STACK_NONE=y, the value of __reserved
field in zen_patch_rev union on the stack may be garbage. If so, it will
prevent correct microcode check when consulting p.ucode_rev, resulting in
incorrect mitigation selection.
This is a stable-only fix.
Cc: <stable@vger.kernel.org>
Signed-off-by: Michael Zhivich <mzhivich@akamai.com>
Fixes: 7a0395f6607a5 ("x86/bugs: Add a Transient Scheduler Attacks mitigation")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index efd42ee9d1cc..4810271302d0 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -378,6 +378,8 @@ static bool amd_check_tsa_microcode(void) p.model = c->x86_model; p.ext_model = c->x86_model >> 4; p.stepping = c->x86_stepping; + /* reserved bits are expected to be 0 in test below */ + p.__reserved = 0; if (cpu_has(c, X86_FEATURE_ZEN3) || cpu_has(c, X86_FEATURE_ZEN4)) { |