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    Subject[PATCH 5.10 052/103] perf/x86/intel/uncore: Fix integer overflow on 23 bit left shift of a u32
    Date
    From: Colin Ian King <colin.king@canonical.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@canonical.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
    Link: https://lore.kernel.org/r/20210706114553.28249-1-colin.king@canonical.com
    Signed-off-by: Sasha Levin <sashal@kernel.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 9c936d06fb61..2701f87a9a7c 100644
    --- a/arch/x86/events/intel/uncore_snbep.c
    +++ b/arch/x86/events/intel/uncore_snbep.c
    @@ -4669,7 +4669,7 @@ 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;
    --
    2.30.2


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