Constants for CXL capability should not change

When CXL capability decoding was upgraded to revision 2 by commit
c0ccce1b4cd5b42b17f2e8f7bae4031c311677ff, the value of PCI_CXL_DEV_LEN
in lib/header.h has changed.

This is probably not a good idea - programs using libpci can depend
on the exact value of this constant.

Let us revert PCI_CXL_DEV_LEN to the original value for revision 1
and add PCI_CXL_DEV_LEN_REV2 for the next revision.

Also, fixed a bug in the decoder which caused it to read past the
end of the buffer for a capability which is declared as revision 2,
but too short.

diff --git a/lib/header.h b/lib/header.h
index 2bace9357f3fea3e817c2f537b70c8f8cc0f6f67..58fe7dfef79b1e69ff4bf2fa5975ffc7a5c50554 100644 (file)
--- a/lib/header.h
+++ b/lib/header.h
@@ -1076,7 +1076,8 @@
 #define PCI_DVSEC_ID_CXL       0       /* Designated Vendor-Specific ID for Intel CXL */
 
 /* PCIe CXL Designated Vendor-Specific Capabilities for Devices: Control, Status */
-#define PCI_CXL_DEV_LEN 0x3c /* CXL Device DVSEC Length */
+#define PCI_CXL_DEV_LEN                0x38    /* CXL Device DVSEC Length for Rev1 */
+#define PCI_CXL_DEV_LEN_REV2           0x3c    /* ... for Rev2 */
 #define PCI_CXL_DEV_CAP                        0x0a    /* CXL Capability Register */
 #define  PCI_CXL_DEV_CAP_CACHE         0x0001  /* CXL.cache Protocol Support */
 #define  PCI_CXL_DEV_CAP_IO            0x0002  /* CXL.io Protocol Support */

diff --git a/ls-ecaps.c b/ls-ecaps.c
index 6d2e7b053e90df4379cf2996d42a01192ae833e4..2d7d827218dc2c5ce79ad29de7ed0fb9a37eb3cf 100644 (file)
--- a/ls-ecaps.c
+++ b/ls-ecaps.c
@@ -718,14 +718,11 @@ dvsec_cxl_device(struct device *d, int rev, int where, int len)
   u64 range_base, range_size;
   u16 w;
 
-  if (len < 0x38)
-    return;
-
   /* Legacy 1.1 revs aren't handled */
   if (rev == 0)
     return;
 
-  if (rev >= 1)
+  if (rev >= 1 && len >= PCI_CXL_DEV_LEN)
     {
       w = get_conf_word(d, where + PCI_CXL_DEV_CAP);
       printf("\t\tCXLCap:\tCache%c IO%c Mem%c MemHWInit%c HDMCount %d Viral%c\n",
@@ -788,7 +785,7 @@ dvsec_cxl_device(struct device *d, int rev, int where, int len)
       cxl_range(range_base, range_size, 2);
     }
 
-  if (rev >= 2)
+  if (rev >= 2 && len >= PCI_CXL_DEV_LEN_REV2)
     {
       w = get_conf_word(d, where + PCI_CXL_DEV_CAP3);
       printf("\t\tCXLCap3:\tDefaultVolatile HDM State After:\tColdReset%c WarmReset%c HotReset%c HotResetConfigurability%c\n",
@@ -799,7 +796,7 @@ dvsec_cxl_device(struct device *d, int rev, int where, int len)
     }
 
   // Unparsed data
-  if (len > PCI_CXL_DEV_LEN)
+  if (len > PCI_CXL_DEV_LEN_REV2)
     printf("\t\t<?>\n");
 }