From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v7 9/9] x86/microcode/AMD: Check the equivalence table size when scanning it
Date: Tue, 19 Jun 2018 20:47:39 +0200 [thread overview]
Message-ID: <c23d04b8d01c8e1e35f30c0684918590ecbc9fe4.1529424596.git.mail@maciej.szmigiero.name> (raw)
In-Reply-To: <cover.1529424596.git.mail@maciej.szmigiero.name>
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 10aabd9d3121..7548dfcf12b0 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -40,6 +40,7 @@
static struct equiv_cpu_table {
struct equiv_cpu_entry *table;
+ unsigned int entries;
} equiv_table;
/*
@@ -65,12 +66,18 @@ 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;
}
@@ -312,7 +319,8 @@ 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;
@@ -583,20 +591,21 @@ 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_table.table, uci->cpu_sig.sig);
+ return find_equiv_id(equiv_table.table, equiv_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_table.table);
- while (equiv_table.table[i].equiv_cpu != 0) {
+ for (i = 0; i < equiv_table.entries &&
+ equiv_table.table[i].equiv_cpu != 0; i++)
if (equiv_cpu == equiv_table.table[i].equiv_cpu)
return equiv_table.table[i].installed_cpu;
- i++;
- }
+
return 0;
}
@@ -740,6 +749,7 @@ static unsigned int install_equiv_cpu_table(const u8 *buf, size_t buf_size)
}
memcpy(equiv_table.table, buf + CONTAINER_HDR_SZ, equiv_tbl_len);
+ equiv_table.entries = equiv_tbl_len / sizeof(struct equiv_cpu_entry);
return equiv_tbl_len;
}
@@ -748,6 +758,7 @@ static void free_equiv_cpu_table(void)
{
vfree(equiv_table.table);
equiv_table.table = NULL;
+ equiv_table.entries = 0;
}
static void cleanup(void)
prev parent reply other threads:[~2018-06-19 18:48 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-19 18:47 [PATCH v7 0/9] x86/microcode/AMD: Check microcode file sanity before loading it Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 1/9] x86/microcode/AMD: Subtract SECTION_HDR_SIZE from file leftover length Maciej S. Szmigiero
2018-11-19 10:12 ` [tip:x86/microcode] " tip-bot for Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 2/9] x86/microcode/AMD: Add microcode container data checking functions Maciej S. Szmigiero
2018-11-19 10:13 ` [tip:x86/microcode] x86/microcode/AMD: Add microcode container verification tip-bot for Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 3/9] x86/microcode/AMD: Integrate verify_patch_size() into verify_patch() Maciej S. Szmigiero
2018-06-21 8:36 ` Borislav Petkov
2018-06-22 22:32 ` [PATCH 1/2] " Maciej S. Szmigiero
2018-06-22 22:33 ` [PATCH 2/2] x86/microcode/AMD: Check patch size for all known CPU families Maciej S. Szmigiero
2018-06-25 18:37 ` Borislav Petkov
2018-06-25 22:18 ` Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 4/9] x86/microcode/AMD: Check microcode container data in the early loader Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 5/9] x86/microcode/AMD: Split status from data to skip in verify_and_add_patch() Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 6/9] x86/microcode/AMD: Check microcode container data in the late loader Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 7/9] x86/microcode/AMD: Add a reminder about PATCH_MAX_SIZE macro Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 8/9] x86/microcode/AMD: Convert CPU equivalence table variable into a struct Maciej S. Szmigiero
2018-06-19 18:47 ` Maciej S. Szmigiero [this message]
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