{"id":"CVE-2021-47414","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: Flush current cpu icache before other cpus\n\nOn SiFive Unmatched, I recently fell onto the following BUG when booting:\n\n[    0.000000] ftrace: allocating 36610 entries in 144 pages\n[    0.000000] Oops - illegal instruction [#1]\n[    0.000000] Modules linked in:\n[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.13.1+ #5\n[    0.000000] Hardware name: SiFive HiFive Unmatched A00 (DT)\n[    0.000000] epc : riscv_cpuid_to_hartid_mask+0x6/0xae\n[    0.000000]  ra : __sbi_rfence_v02+0xc8/0x10a\n[    0.000000] epc : ffffffff80007240 ra : ffffffff80009964 sp : ffffffff81803e10\n[    0.000000]  gp : ffffffff81a1ea70 tp : ffffffff8180f500 t0 : ffffffe07fe30000\n[    0.000000]  t1 : 0000000000000004 t2 : 0000000000000000 s0 : ffffffff81803e60\n[    0.000000]  s1 : 0000000000000000 a0 : ffffffff81a22238 a1 : ffffffff81803e10\n[    0.000000]  a2 : 0000000000000000 a3 : 0000000000000000 a4 : 0000000000000000\n[    0.000000]  a5 : 0000000000000000 a6 : ffffffff8000989c a7 : 0000000052464e43\n[    0.000000]  s2 : ffffffff81a220c8 s3 : 0000000000000000 s4 : 0000000000000000\n[    0.000000]  s5 : 0000000000000000 s6 : 0000000200000100 s7 : 0000000000000001\n[    0.000000]  s8 : ffffffe07fe04040 s9 : ffffffff81a22c80 s10: 0000000000001000\n[    0.000000]  s11: 0000000000000004 t3 : 0000000000000001 t4 : 0000000000000008\n[    0.000000]  t5 : ffffffcf04000808 t6 : ffffffe3ffddf188\n[    0.000000] status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000002\n[    0.000000] [\u003cffffffff80007240\u003e] riscv_cpuid_to_hartid_mask+0x6/0xae\n[    0.000000] [\u003cffffffff80009474\u003e] sbi_remote_fence_i+0x1e/0x26\n[    0.000000] [\u003cffffffff8000b8f4\u003e] flush_icache_all+0x12/0x1a\n[    0.000000] [\u003cffffffff8000666c\u003e] patch_text_nosync+0x26/0x32\n[    0.000000] [\u003cffffffff8000884e\u003e] ftrace_init_nop+0x52/0x8c\n[    0.000000] [\u003cffffffff800f051e\u003e] ftrace_process_locs.isra.0+0x29c/0x360\n[    0.000000] [\u003cffffffff80a0e3c6\u003e] ftrace_init+0x80/0x130\n[    0.000000] [\u003cffffffff80a00f8c\u003e] start_kernel+0x5c4/0x8f6\n[    0.000000] ---[ end trace f67eb9af4d8d492b ]---\n[    0.000000] Kernel panic - not syncing: Attempted to kill the idle task!\n[    0.000000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---\n\nWhile ftrace is looping over a list of addresses to patch, it always failed\nwhen patching the same function: riscv_cpuid_to_hartid_mask. Looking at the\nbacktrace, the illegal instruction is encountered in this same function.\nHowever, patch_text_nosync, after patching the instructions, calls\nflush_icache_range. But looking at what happens in this function:\n\nflush_icache_range -\u003e flush_icache_all\n                   -\u003e sbi_remote_fence_i\n                   -\u003e __sbi_rfence_v02\n                   -\u003e riscv_cpuid_to_hartid_mask\n\nThe icache and dcache of the current cpu are never synchronized between the\npatching of riscv_cpuid_to_hartid_mask and calling this same function.\n\nSo fix this by flushing the current cpu's icache before asking for the other\ncpus to do the same.","modified":"2026-03-14T11:19:09.953181Z","published":"2024-05-21T15:15:26.887Z","related":["SUSE-SU-2024:2008-1","SUSE-SU-2024:2011-1","SUSE-SU-2024:2019-1","SUSE-SU-2024:2189-1","SUSE-SU-2024:2190-1"],"references":[{"type":"FIX","url":"https://git.kernel.org/stable/c/427faa29e06f0709476ea1bd59758f997ec8b64e"},{"type":"FIX","url":"https://git.kernel.org/stable/c/bb8958d5dc79acbd071397abb57b8756375fe1ce"},{"type":"FIX","url":"https://git.kernel.org/stable/c/f1c7aa87c423e765e3862349c2f095fdfccdd9b3"}],"affected":[{"database_specific":{"unresolved_ranges":[{"events":[{"introduced":"4.15"},{"fixed":"5.10.73"}]},{"events":[{"introduced":"5.11"},{"fixed":"5.14.12"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc1"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc2"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc3"}]},{"events":[{"introduced":"0"},{"last_affected":"5.15-rc4"}]}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47414.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}