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

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Date:   Tue, 27 Jul 2021 13:58:54 -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>,
        Kan Liang <kan.liang@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: perf/core] perf/x86/intel/uncore: Fix integer overflow on 23
 bit left shift of a u32

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

Commit-ID:     92279a3b11a0a8486ce6b92384ddc0849eb4060f
Gitweb:        https://git.kernel.org/tip/92279a3b11a0a8486ce6b92384ddc0849eb4060f
Author:        Colin Ian King <colin.king@...onical.com>
AuthorDate:    Tue, 06 Jul 2021 12:45:53 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 16 Jul 2021 18:46:48 +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>
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 f665b16..9a178a9 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -4834,7 +4834,7 @@ static int snr_uncore_mmio_map(struct intel_uncore_box *box,
 		return -ENODEV;
 
 	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;