Minor change to avoid potental overflow accessing pci option roms

PATCH New Zhenzhong Duan 1 participant 1 message Aug 20, 2013

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Zhenzhong Duan

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2013-08-20 06:38 UTC #0 lore raw

PATCH v2 1/1 Minor change to avoid potental overflow accessing pci option roms

When scan pci option roms space, there is possibility to access beyond OPTIONROM_PHYSICAL_END for 2K.

This patch makes the code robust though there are other checks such as 0x55AA signature.

Bug was found by code inspection.

v2: Add description per Konrad's suggestion, thanks.

Signed-off-by Zhenzhong Duan <[email protected]>

---
 tools/firmware/rombios/rombios.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

tools/firmware/rombios/rombios.c +2 -2

index 057aced..f5ac33e 100644
@@ -10648,7 +10648,7 @@ rom_scan_increment:
   add  cx, ax
   pop  ax       ;; Restore AX
   cmp  cx, ax
-  jbe  rom_scan_loop
+  jb  rom_scan_loop
 
   xor  ax, ax   ;; Restore DS back to 0000:
   mov  ds, ax

@@ -11022,7 +11022,7 @@ post_default_ints:
   call post_init_pic
 
   mov  cx, #0xc000  ;; init vga bios
-  mov  ax, #0xc780
+  mov  ax, #0xc800
   call rom_scan
 
   call _print_bios_banner

Signature · 1 line

1.7.3