| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.17 056/319] x86, pageattr: Prevent overflow in slow_virt_to_phys() for X86_PAE | Date | Wed, 12 Nov 2014 10:13:14 +0900 |
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3.17-stable review patch. If anyone has any objections, please let me know.
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From: Dexuan Cui <decui@microsoft.com>
commit d1cd1210834649ce1ca6bafe5ac25d2f40331343 upstream.
pte_pfn() returns a PFN of long (32 bits in 32-PAE), so "long << PAGE_SHIFT" will overflow for PFNs above 4GB.
Due to this issue, some Linux 32-PAE distros, running as guests on Hyper-V, with 5GB memory assigned, can't load the netvsc driver successfully and hence the synthetic network device can't work (we can use the kernel parameter mem=3000M to work around the issue).
Cast pte_pfn() to phys_addr_t before shifting.
Fixes: "commit d76565344512: x86, mm: Create slow_virt_to_phys()" Signed-off-by: Dexuan Cui <decui@microsoft.com> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: gregkh@linuxfoundation.org Cc: linux-mm@kvack.org Cc: olaf@aepfle.de Cc: apw@canonical.com Cc: jasowang@redhat.com Cc: dave.hansen@intel.com Cc: riel@redhat.com Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1414580017-27444-1-git-send-email-decui@microsoft.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/x86/mm/pageattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -409,7 +409,7 @@ phys_addr_t slow_virt_to_phys(void *__vi psize = page_level_size(level); pmask = page_level_mask(level); offset = virt_addr & ~pmask; - phys_addr = pte_pfn(*pte) << PAGE_SHIFT; + phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT; return (phys_addr | offset); } EXPORT_SYMBOL_GPL(slow_virt_to_phys);
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