linux-kernel - [tip: perf/urgent] perf/x86/intel/uncore: Fix integer overflow on 23 bit left shift of a u32

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Message-ID: <162996392716.25758.13184611014584247262.tip-bot2@tip-bot2>
Date:   Thu, 26 Aug 2021 07:45:27 -0000
From:   "tip-bot2 for Colin Ian King" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Colin Ian King <colin.king@...onical.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Kan Liang <kan.liang@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: perf/urgent] perf/x86/intel/uncore: Fix integer overflow on 23
 bit left shift of a u32

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     0b3a8738b76fe2087f7bc2bd59f4c78504c79180
Gitweb:        https://git.kernel.org/tip/0b3a8738b76fe2087f7bc2bd59f4c78504c79180
Author:        Colin Ian King <colin.king@...onical.com>
AuthorDate:    Tue, 06 Jul 2021 12:45:53 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Thu, 26 Aug 2021 08:58:02 +02:00

perf/x86/intel/uncore: Fix integer overflow on 23 bit left shift of a u32

The u32 variable pci_dword is being masked with 0x1fffffff and then left
shifted 23 places. The shift is a u32 operation,so a value of 0x200 or
more in pci_dword will overflow the u32 and only the bottow 32 bits
are assigned to addr. I don't believe this was the original intent.
Fix this by casting pci_dword to a resource_size_t to ensure no
overflow occurs.

Note that the mask and 12 bit left shift operation does not need this
because the mask SNR_IMC_MMIO_MEM0_MASK and shift is always a 32 bit
value.

Fixes: ee49532b38dd ("perf/x86/intel/uncore: Add IMC uncore support for Snow Ridge")
Addresses-Coverity: ("Unintentional integer overflow")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
Link: https://lore.kernel.org/r/20210706114553.28249-1-colin.king@canonical.com
---
 arch/x86/events/intel/uncore_snbep.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 609c24a..c682b09 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -4811,7 +4811,7 @@ static void __snr_uncore_mmio_init_box(struct intel_uncore_box *box,
 		return;
 
 	pci_read_config_dword(pdev, SNR_IMC_MMIO_BASE_OFFSET, &pci_dword);
-	addr = (pci_dword & SNR_IMC_MMIO_BASE_MASK) << 23;
+	addr = ((resource_size_t)pci_dword & SNR_IMC_MMIO_BASE_MASK) << 23;
 
 	pci_read_config_dword(pdev, mem_offset, &pci_dword);
 	addr |= (pci_dword & SNR_IMC_MMIO_MEM0_MASK) << 12;