linux-kernel - [PATCH 5.4 27/48] perf/x86/intel/uncore: Fix integer overflow on 23 bit left shift of a u32

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Date:   Wed,  1 Sep 2021 14:28:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, 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>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 27/48] perf/x86/intel/uncore: Fix integer overflow on 23 bit left shift of a u32

From: Colin Ian King <colin.king@...onical.com>

[ Upstream commit 0b3a8738b76fe2087f7bc2bd59f4c78504c79180 ]

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
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 40751af62dd3..9096a1693942 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -4382,7 +4382,7 @@ 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, SNR_IMC_MMIO_MEM0_OFFSET, &pci_dword);
 	addr |= (pci_dword & SNR_IMC_MMIO_MEM0_MASK) << 12;
-- 
2.30.2