linux-kernel - [PATCH] x86/MCE/AMD: avoid shift-out-of-bounds when decoding bank

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Date:   Fri, 27 Jan 2023 15:16:01 +0000
From:   Muralidhara M K <muralimk@....com>
To:     <linux-edac@...r.kernel.org>, <x86@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <bp@...en8.de>, <mingo@...hat.com>,
        <mchehab@...nel.org>, <yazen.ghannam@....com>, <nchatrad@....com>,
        Muralidhara M K <muralimk@....com>
Subject: [PATCH] x86/MCE/AMD: avoid shift-out-of-bounds when decoding bank

Fix dump stack due to shift-out-of-bounds in
arch/x86/kernel/cpu/mce/amd.c when UBSAN configs are enabled.

Maximum number of MCA banks is 64 (MAX_NR_BANKS) from commit
a0bc32b3cacf ("x86/mce: Increase maximum number of banks to 64").

But the driver uses 32 bit variable(bank_map and smca_misc_banks_map)
to manage the list of banks which causes out-of-bounds warnings.

So, fix would be to change the data types of bank_map and
smca_misc_banks_map in addition to switch the bit mask assignment to
use BIT_ULL() for 64-bit type.

Signed-off-by: Muralidhara M K <muralimk@....com>
---
 arch/x86/kernel/cpu/mce/amd.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 10fb5b5c9efa..5518272061bf 100644
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -235,10 +235,10 @@ static DEFINE_PER_CPU(struct threshold_bank **, threshold_banks);
  * A list of the banks enabled on each logical CPU. Controls which respective
  * descriptors to initialize later in mce_threshold_create_device().
  */
-static DEFINE_PER_CPU(unsigned int, bank_map);
+static DEFINE_PER_CPU(u64, bank_map);
 
 /* Map of banks that have more than MCA_MISC0 available. */
-static DEFINE_PER_CPU(u32, smca_misc_banks_map);
+static DEFINE_PER_CPU(u64, smca_misc_banks_map);
 
 static void amd_threshold_interrupt(void);
 static void amd_deferred_error_interrupt(void);
@@ -267,7 +267,7 @@ static void smca_set_misc_banks_map(unsigned int bank, unsigned int cpu)
 		return;
 
 	if (low & MASK_BLKPTR_LO)
-		per_cpu(smca_misc_banks_map, cpu) |= BIT(bank);
+		per_cpu(smca_misc_banks_map, cpu) |= BIT_ULL(bank);
 
 }
 
@@ -528,7 +528,7 @@ static u32 smca_get_block_address(unsigned int bank, unsigned int block,
 	if (!block)
 		return MSR_AMD64_SMCA_MCx_MISC(bank);
 
-	if (!(per_cpu(smca_misc_banks_map, cpu) & BIT(bank)))
+	if (!(per_cpu(smca_misc_banks_map, cpu) & BIT_ULL(bank)))
 		return 0;
 
 	return MSR_AMD64_SMCA_MCx_MISCy(bank, block - 1);
@@ -572,7 +572,7 @@ prepare_threshold_block(unsigned int bank, unsigned int block, u32 addr,
 	int new;
 
 	if (!block)
-		per_cpu(bank_map, cpu) |= (1 << bank);
+		per_cpu(bank_map, cpu) |= BIT_ULL(bank);
 
 	memset(&b, 0, sizeof(b));
 	b.cpu			= cpu;
@@ -884,7 +884,7 @@ static void amd_threshold_interrupt(void)
 		return;
 
 	for (bank = 0; bank < this_cpu_read(mce_num_banks); ++bank) {
-		if (!(per_cpu(bank_map, cpu) & (1 << bank)))
+		if (!(per_cpu(bank_map, cpu) & BIT_ULL(bank)))
 			continue;
 
 		first_block = bp[bank]->blocks;
@@ -1362,7 +1362,7 @@ int mce_threshold_create_device(unsigned int cpu)
 		return -ENOMEM;
 
 	for (bank = 0; bank < numbanks; ++bank) {
-		if (!(this_cpu_read(bank_map) & (1 << bank)))
+		if (!(this_cpu_read(bank_map) & BIT_ULL(bank)))
 			continue;
 		err = threshold_create_bank(bp, cpu, bank);
 		if (err) {
-- 
2.25.1