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@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

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 609c24aec71a77fef399b88bd35210caf6cedbb3..c682b09b18fa00d75adf7989e4129215e293deac 100644 (file)
--- 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;