In the Linux kernel, the following vulnerability has been resolved:
arm64: Restrict CPU_BIG_ENDIAN to GNU as or LLVM IAS 15.x or newer
Prior to LLVM 15.0.0, LLVM's integrated assembler would incorrectly byte-swap NOP when compiling for big-endian, and the resulting series of bytes happened to match the encoding of FNMADD S21, S30, S0, S0.
This went unnoticed until commit:
34f66c4c4d5518c1 ("arm64: Use a positive cpucap for FP/SIMD")
Prior to that commit, the kernel would always enable the use of FPSIMD early in boot when __cpu_setup() initialized CPACR_EL1, and so usage of FNMADD within the kernel was not detected, but could result in the corruption of user or kernel FPSIMD state.
After that commit, the instructions happen to trap during boot prior to FPSIMD being detected and enabled, e.g.
| Unhandled 64-bit el1h sync exception on CPU0, ESR 0x000000001fe00000 -- ASIMD | CPU: 0 PID: 0 Comm: swapper Not tainted 6.6.0-rc3-00013-g34f66c4c4d55 #1 | Hardware name: linux,dummy-virt (DT) | pstate: 400000c9 (nZcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : __pi_strcmp+0x1c/0x150 | lr : populate_properties+0xe4/0x254 | sp : ffffd014173d3ad0 | x29: ffffd014173d3af0 x28: fffffbfffddffcb8 x27: 0000000000000000 | x26: 0000000000000058 x25: fffffbfffddfe054 x24: 0000000000000008 | x23: fffffbfffddfe000 x22: fffffbfffddfe000 x21: fffffbfffddfe044 | x20: ffffd014173d3b70 x19: 0000000000000001 x18: 0000000000000005 | x17: 0000000000000010 x16: 0000000000000000 x15: 00000000413e7000 | x14: 0000000000000000 x13: 0000000000001bcc x12: 0000000000000000 | x11: 00000000d00dfeed x10: ffffd414193f2cd0 x9 : 0000000000000000 | x8 : 0101010101010101 x7 : ffffffffffffffc0 x6 : 0000000000000000 | x5 : 0000000000000000 x4 : 0101010101010101 x3 : 000000000000002a | x2 : 0000000000000001 x1 : ffffd014171f2988 x0 : fffffbfffddffcb8 | Kernel panic - not syncing: Unhandled exception | CPU: 0 PID: 0 Comm: swapper Not tainted 6.6.0-rc3-00013-g34f66c4c4d55 #1 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0xec/0x108 | show_stack+0x18/0x2c | dump_stack_lvl+0x50/0x68 | dump_stack+0x18/0x24 | panic+0x13c/0x340 | el1t_64_irq_handler+0x0/0x1c | el1_abort+0x0/0x5c | el1h_64_sync+0x64/0x68 | __pi_strcmp+0x1c/0x150 | unflatten_dt_nodes+0x1e8/0x2d8 | __unflatten_device_tree+0x5c/0x15c | unflatten_device_tree+0x38/0x50 | setup_arch+0x164/0x1e0 | start_kernel+0x64/0x38c | __primary_switched+0xbc/0xc4
Restrict CONFIG_CPU_BIG_ENDIAN to a known good assembler, which is either GNU as or LLVM's IAS 15.0.0 and newer, which contains the linked commit.
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade linux | Jul 30, 2024 | May 21, 2024 |
| Redhat_linux | — | No solution exists | Jul 9, 2025 | May 21, 2024 |
| Suse | — | Upgrade kernel-azure-extraUpgrade kernel-defaultUpgrade kernel-syms-rtUpgrade cluster-md-kmp-64kbUpgrade dtb-armUpgrade dtb-broadcomUpgrade kernel-kvmsmall-vdsoUpgrade kernel-rt-extraUpgrade reiserfs-kmp-rtUpgrade dtb-sprdUpgrade gfs2-kmp-defaultUpgrade dtb-amdUpgrade kernel-rt_debug-livepatch-develUpgrade kernel-rt_debug-vdsoUpgrade kernel-default-livepatch-develUpgrade dlm-kmp-azureUpgrade dtb-apmUpgrade kernel-debug-vdsoUpgrade dlm-kmp-rtUpgrade reiserfs-kmp-64kbUpgrade cluster-md-kmp-defaultUpgrade dlm-kmp-defaultUpgrade dtb-renesasUpgrade dtb-nvidiaUpgrade dtb-hisiliconUpgrade kernel-rt-vdsoUpgrade kernel-docsUpgrade kernel-kvmsmall-livepatch-develUpgrade kselftests-kmp-defaultUpgrade dtb-appleUpgrade kernel-rt_debugUpgrade ocfs2-kmp-64kbUpgrade dtb-amlogicUpgrade kernel-source-rtUpgrade kernel-azure-vdsoUpgrade kernel-rt-livepatch-develUpgrade dtb-marvellUpgrade kernel-default-baseUpgrade kernel-rt-optionalUpgrade kernel-debug-develUpgrade kernel-debug-livepatch-develUpgrade ocfs2-kmp-azureUpgrade dtb-socionextUpgrade kselftests-kmp-rtUpgrade kernel-docs-htmlUpgrade kernel-64kb-optionalUpgrade kernel-symsUpgrade kernel-debugUpgrade kernel-64kb-extraUpgrade reiserfs-kmp-defaultUpgrade kernel-rt-develUpgrade kernel-default-develUpgrade kernel-kvmsmallUpgrade kernel-default-optionalUpgrade dtb-mediatekUpgrade dlm-kmp-64kbUpgrade kernel-64kb-develUpgrade cluster-md-kmp-rtUpgrade ocfs2-kmp-defaultUpgrade kselftests-kmp-azureUpgrade kernel-default-extraUpgrade kernel-azureUpgrade kernel-kvmsmall-develUpgrade kernel-develUpgrade kernel-azure-optionalUpgrade kernel-obs-buildUpgrade kernel-sourceUpgrade dtb-freescaleUpgrade reiserfs-kmp-azureUpgrade kselftests-kmp-64kbUpgrade kernel-syms-azureUpgrade gfs2-kmp-rtUpgrade ocfs2-kmp-rtUpgrade kernel-obs-qaUpgrade kernel-rtUpgrade dtb-exynosUpgrade dtb-rockchipUpgrade kernel-azure-develUpgrade kernel-zfcpdumpUpgrade kernel-rt_debug-develUpgrade kernel-default-vdsoUpgrade kernel-64kb-livepatch-develUpgrade cluster-md-kmp-azureUpgrade dtb-lgUpgrade kernel-azure-livepatch-develUpgrade dtb-qcomUpgrade kernel-macrosUpgrade dtb-caviumUpgrade dtb-allwinnerUpgrade kernel-default-base-rebuildUpgrade kernel-64kbUpgrade dtb-xilinxUpgrade gfs2-kmp-64kbUpgrade kernel-devel-azureUpgrade kernel-source-vanillaUpgrade gfs2-kmp-azureUpgrade dtb-alteraUpgrade dtb-amazonUpgrade kernel-source-azureUpgrade kernel-default-livepatchUpgrade kernel-devel-rt | Aug 9, 2024 | May 21, 2024 |
| Ubuntu | — | Upgrade linux-xilinx-zynqmpUpgrade linux-oracle-5.15Upgrade linux-azure-5.15Upgrade linux-ibmUpgrade linux-bluefieldUpgrade linux-intel-iot-realtimeUpgrade linux-kvmUpgrade linux-fipsUpgrade linux-riscv-5.15Upgrade linux-gcpUpgrade linux-nvidia-tegraUpgrade linux-intel-iotgUpgrade linux-gkeUpgrade linux-lowlatency-hwe-5.15Upgrade linux-gkeopUpgrade linux-azure-fdeUpgrade linux-gcp-5.15Upgrade linux-azure-fde-5.15Upgrade linux-aws-fipsUpgrade linux-ibm-5.15Upgrade linux-intel-iotg-5.15Upgrade linux-realtimeUpgrade linux-oracleUpgrade linux-nvidiaUpgrade linux-hwe-5.15Upgrade linuxUpgrade linux-awsUpgrade linux-gkeop-5.15Upgrade linux-aws-5.15Upgrade linux-nvidia-6.5Upgrade linux-raspiUpgrade linux-azureUpgrade linux-nvidia-tegra-5.15Upgrade linux-gcp-fipsUpgrade linux-lowlatencyUpgrade linux-nvidia-tegra-igx | Nov 19, 2024 | May 21, 2024 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Jan 20, 2025 | May 21, 2024 |
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