Re: [SeaBIOS] [PATCH 2/2] seabios: pciinit: fix overflow when bar allocation.

[Kevin O'Connor]

On Mon, Jul 26, 2010 at 02:02:46PM +0900, Isaku Yamahata wrote:
 When allocating bar, overflow can occur.
 So add overflow check and don't allocate bar if overflowed.
 Overflow check is ugly, but necessary.
 Another suggested way is to change related variables u64 from u32
 thus overflow can't occur because the related value are all u32 addressable.
 Anyway even with u64, it is necessary to the resulted value > max_u32.
I wonder if we could create malloc zones for this and then use
pmm_alloc.  The pmm_alloc function already handles overflow and
alignments.

One difficulty, though, is that pmm_alloc doesn't guarentee linear
allocations, and it looks like pci_bios_init_device_bridge assumes
this.

-Kevin

[PATCH 2/2] seabios: pciinit: fix overflow when bar allocation.

[Isaku Yamahata]

On Mon, Jul 26, 2010 at 09:45:42PM -0400, Kevin O'Connor wrote:
 On Mon, Jul 26, 2010 at 02:02:46PM +0900, Isaku Yamahata wrote:
 > When allocating bar, overflow can occur.
 > So add overflow check and don't allocate bar if overflowed.
 > Overflow check is ugly, but necessary.
 > Another suggested way is to change related variables u64 from u32
 > thus overflow can't occur because the related value are all u32 addressable.
 > Anyway even with u64, it is necessary to the resulted value > max_u32.
 
 I wonder if we could create malloc zones for this and then use
 pmm_alloc.  The pmm_alloc function already handles overflow and
 alignments.
 
 One difficulty, though, is that pmm_alloc doesn't guarentee linear
 allocations, and it looks like pci_bios_init_device_bridge assumes
 this.
Yes, contiguous allocation is necessary for bridge filtering.
Anyway I'll give pmm_malloc() a try and see what can be done.
-- 
yamahata