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| author | Thomas Gleixner <tglx@linutronix.de> | 2010-02-25 16:42:11 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2010-02-26 10:24:59 +0100 |
| commit | dcde507ee290ee07509dc81c65eaec9e20da2279 (patch) | |
| tree | 9245a9db33b64ae86ae75c98ff3c7eab56d30b52 /arch | |
| parent | 669d6ece85f7750c01803662c8d8d3db8f726361 (diff) | |
| download | lwn-dcde507ee290ee07509dc81c65eaec9e20da2279.tar.gz lwn-dcde507ee290ee07509dc81c65eaec9e20da2279.zip | |
x86: pci: Prevent mmconfig memory corruption
commit ff097ddd4 (x86/PCI: MMCONFIG: manage pci_mmcfg_region as
a list, not a table) introduced a nasty memory corruption when
pci_mmcfg_list is empty.
pci_mmcfg_check_end_bus_number() dereferences
pci_mmcfg_list.prev even when the list is empty. The following
write hits some variable near to pci_mmcfg_list.
Further down a similar problem exists, where cfg->list.next is
dereferenced unconditionally and a comparison with some variable
near to pci_mmcfg_list happens.
Add a check for the last element into the for_each_entry() loop
and remove all the other crappy logic which is just a leftover
of the old array based code which was replaced by the list
conversion.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
LKML-Reference: <alpine.LFD.2.00.1002251638230.4245@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/pci/mmconfig-shared.c | 17 |
1 files changed, 6 insertions, 11 deletions
diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c index b19d1e54201e..8f3f9a50b1e0 100644 --- a/arch/x86/pci/mmconfig-shared.c +++ b/arch/x86/pci/mmconfig-shared.c @@ -303,22 +303,17 @@ static void __init pci_mmcfg_check_end_bus_number(void) { struct pci_mmcfg_region *cfg, *cfgx; - /* last one*/ - cfg = list_entry(pci_mmcfg_list.prev, typeof(*cfg), list); - if (cfg) - if (cfg->end_bus < cfg->start_bus) - cfg->end_bus = 255; - - if (list_is_singular(&pci_mmcfg_list)) - return; - - /* don't overlap please */ + /* Fixup overlaps */ list_for_each_entry(cfg, &pci_mmcfg_list, list) { if (cfg->end_bus < cfg->start_bus) cfg->end_bus = 255; + /* Don't access the list head ! */ + if (cfg->list.next == &pci_mmcfg_list) + break; + cfgx = list_entry(cfg->list.next, typeof(*cfg), list); - if (cfg != cfgx && cfg->end_bus >= cfgx->start_bus) + if (cfg->end_bus >= cfgx->start_bus) cfg->end_bus = cfgx->start_bus - 1; } } |