From: Gregory Price <gourry@gourry.net> mainline inclusion from mainline-v6.18-rc3 commit 607b9fb2ce248cc5b633c5949e0153838992c152 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/11500 CVE: CVE-2025-68313 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... There's an issue with RDSEED's 16-bit and 32-bit register output variants on Zen5 which return a random value of 0 "at a rate inconsistent with randomness while incorrectly signaling success (CF=1)". Search the web for AMD-SB-7055 for more detail. Add a fix glue which checks microcode revisions. [ bp: Add microcode revisions checking, rewrite. ] Cc: stable@vger.kernel.org Signed-off-by: Gregory Price <gourry@gourry.net> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20251018024010.4112396-1-gourry@gourry.net Signed-off-by: Bowen You <youbowen2@huawei.com> --- arch/x86/kernel/cpu/amd.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index d7a8f8bb9026..9990e058b6e8 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1128,8 +1128,18 @@ static void init_amd_zen4(struct cpuinfo_x86 *c) } } +static const struct x86_cpu_id zen5_rdseed_microcode[] = { + ZEN_MODEL_STEP_UCODE(0x1a, 0x02, 0x1, 0x0b00215a), + ZEN_MODEL_STEP_UCODE(0x1a, 0x11, 0x0, 0x0b101054), +}; + static void init_amd_zen5(struct cpuinfo_x86 *c) { + if (!x86_match_min_microcode_rev(zen5_rdseed_microcode)) { + clear_cpu_cap(c, X86_FEATURE_RDSEED); + msr_clear_bit(MSR_AMD64_CPUID_FN_7, 18); + pr_emerg_once("RDSEED32 is broken. Disabling the corresponding CPUID bit.\n"); + } } static void init_amd(struct cpuinfo_x86 *c) -- 2.34.1