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devicemodel: hw: pci: gvt: Fix out of bounds error #8118

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devicemodel: hw: pci: gvt: Fix out of bounds error #8118

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16 changes: 15 additions & 1 deletion devicemodel/hw/pci/gvt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -256,7 +256,21 @@ gvt_init_config(struct pci_gvt *gvt)
/* capability */
pci_set_cfgdata8(gvt->gvt_pi, PCIR_CAP_PTR, gvt->host_config[0x34]);
cap_ptr = gvt->host_config[0x34];
while (cap_ptr != 0) {
/*
hw/pci/gvt.c:263:41: error: array subscript 257 is above array bounds of ‘uint8_t[256]’ {aka ‘unsigned char[256]’} [-Werror=array-bounds]
263 | gvt->host_config[cap_ptr + 4]);
| ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
hw/pci/gvt.c:48:17: note: while referencing ‘host_config’
48 | uint8_t host_config[PCI_REGMAX+1];
| ^~~~~~~~~~~

With the additional condition cap_ptr < PCI_REGMAX - 16 it
is ensured that we never read config data from places we
shouln't read from.

12 (offset) + 4 (pci_set_cfgdata32) = 16
*/
while (cap_ptr != 0 && cap_ptr < PCI_REGMAX - 16) {
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Should we change the pci_set_cfgdata32 to pci_set_cfgdata8. And if the cap_ptr != 0 but exceeds the "PCI_REGMAX - 16" then print some warning logs as some capabilities are lost.

@yakuizhao to comment

pci_set_cfgdata32(gvt->gvt_pi, cap_ptr,
gvt->host_config[cap_ptr]);
pci_set_cfgdata32(gvt->gvt_pi, cap_ptr + 4,
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