switchtec: Fix Spectre v1 vulnerability
p.port can is indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/pci/switch/switchtec.c:912 ioctl_port_to_pff() warn: potential spectre issue 'pcfg->dsp_pff_inst_id' [r] Fix this by sanitizing p.port before using it to index pcfg->dsp_pff_inst_id Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Logan Gunthorpe <logang@deltatee.com> Cc: stable@vger.kernel.org
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@ -14,6 +14,8 @@
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#include <linux/poll.h>
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#include <linux/wait.h>
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#include <linux/nospec.h>
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MODULE_DESCRIPTION("Microsemi Switchtec(tm) PCIe Management Driver");
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MODULE_VERSION("0.1");
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MODULE_LICENSE("GPL");
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@ -909,6 +911,8 @@ static int ioctl_port_to_pff(struct switchtec_dev *stdev,
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default:
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if (p.port > ARRAY_SIZE(pcfg->dsp_pff_inst_id))
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return -EINVAL;
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p.port = array_index_nospec(p.port,
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ARRAY_SIZE(pcfg->dsp_pff_inst_id) + 1);
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p.pff = ioread32(&pcfg->dsp_pff_inst_id[p.port - 1]);
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break;
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}
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