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

From: Colin King
Date: Tue Jul 06 2021 - 08:10:54 EST

From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

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

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@xxxxxxxxxxxxx>
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 48419dad3b17..7518143850df 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -4827,7 +4827,7 @@ 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;