Messages in this thread Patch in this message | | | From | "Maciej S. Szmigiero" <> | Subject | [PATCH v5 6/6] x86/microcode/AMD: Check the equivalence table size when scanning it | Date | Mon, 23 Apr 2018 23:34:11 +0200 |
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Currently, the code scanning the CPU equivalence table read from a microcode container file assumes that it actually contains a terminating zero entry. Let's check also the size of this table to make sure that we don't read past it in case it actually doesn't.
Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name> --- arch/x86/kernel/cpu/microcode/amd.c | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c index 2df366cc71ce..5ba933ce1d51 100644 --- a/arch/x86/kernel/cpu/microcode/amd.c +++ b/arch/x86/kernel/cpu/microcode/amd.c @@ -39,6 +39,7 @@ #include <asm/msr.h> static struct equiv_cpu_entry *equiv_cpu_table; +static unsigned int equiv_cpu_table_entries; /* * This points to the current valid container of microcode patches which we will @@ -63,12 +64,18 @@ static u8 amd_ucode_patch[PATCH_MAX_SIZE]; static const char ucode_path[] __maybe_unused = "kernel/x86/microcode/AuthenticAMD.bin"; -static u16 find_equiv_id(struct equiv_cpu_entry *equiv_table, u32 sig) +static u16 find_equiv_id(const struct equiv_cpu_entry *equiv_table, + unsigned int equiv_table_entries, u32 sig) { - for (; equiv_table && equiv_table->installed_cpu; equiv_table++) { - if (sig == equiv_table->installed_cpu) - return equiv_table->equiv_cpu; - } + unsigned int i; + + if (!equiv_table) + return 0; + + for (i = 0; i < equiv_table_entries && equiv_table[i].installed_cpu; + i++) + if (sig == equiv_table[i].installed_cpu) + return equiv_table[i].equiv_cpu; return 0; } @@ -237,7 +244,8 @@ static size_t parse_container(u8 *ucode, size_t size, struct cont_desc *desc) eq = (struct equiv_cpu_entry *)(buf + CONTAINER_HDR_SZ); /* Find the equivalence ID of our CPU in this table: */ - eq_id = find_equiv_id(eq, desc->cpuid_1_eax); + eq_id = find_equiv_id(eq, equiv_tbl_len / sizeof(*eq), + desc->cpuid_1_eax); buf += CONTAINER_HDR_SZ; buf += equiv_tbl_len; @@ -499,20 +507,21 @@ void reload_ucode_amd(void) static u16 __find_equiv_id(unsigned int cpu) { struct ucode_cpu_info *uci = ucode_cpu_info + cpu; - return find_equiv_id(equiv_cpu_table, uci->cpu_sig.sig); + return find_equiv_id(equiv_cpu_table, equiv_cpu_table_entries, + uci->cpu_sig.sig); } static u32 find_cpu_family_by_equiv_cpu(u16 equiv_cpu) { - int i = 0; + unsigned int i; BUG_ON(!equiv_cpu_table); - while (equiv_cpu_table[i].equiv_cpu != 0) { + for (i = 0; i < equiv_cpu_table_entries && + equiv_cpu_table[i].equiv_cpu != 0; i++) if (equiv_cpu == equiv_cpu_table[i].equiv_cpu) return equiv_cpu_table[i].installed_cpu; - i++; - } + return 0; } @@ -697,6 +706,7 @@ static unsigned int install_equiv_cpu_table(const u8 *buf, size_t buf_size) } memcpy(equiv_cpu_table, buf + CONTAINER_HDR_SZ, equiv_tbl_len); + equiv_cpu_table_entries = equiv_tbl_len / sizeof(struct equiv_cpu_entry); return equiv_tbl_len; } @@ -705,6 +715,7 @@ static void free_equiv_cpu_table(void) { vfree(equiv_cpu_table); equiv_cpu_table = NULL; + equiv_cpu_table_entries = 0; } static void cleanup(void)
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