Messages in this thread Patch in this message | | | From | <> | Subject | [PATCH 1/1] x86/mm: Fix limit mmap() of /dev/mem to valid physical addresses | Date | Mon, 18 Mar 2019 15:46:53 -0700 |
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From: Ralph Campbell <rcampbell@nvidia.com>
If CONFIG_DEBUG_VIRTUAL is enabled, a read or write to /dev/mem can trigger a VIRTUAL_BUG_ON() depending on the value of high_memory. For example:
read_mem() valid_phys_addr_range(p=401f1550, count=8) __pa(high_memory) __phys_addr(x=ffffc88000000000) // __START_KERNEL_map = ffffffff80000000 // y = ffffc88000000000 - ffffffff80000000 VIRTUAL_BUG_ON(phys_addr_valid(400000000000)) // boot_cpu_data.x86_phys_bits=46
Since by design high_memory is outside the range of valid physical addresses, use the non-error checking version __pa_nodebug(high_memory).
Fixes: be62a32044061cb4a3b70a10598e093f1319102e ("x86/mm: Limit mmap() of /dev/mem to valid physical addresses")
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Cc: Craig Bergstrom <craigb@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hans Verkuil <hans.verkuil@cisco.com> Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sander Eikelenboom <linux@eikelenboom.it> Cc: Sean Young <sean@mess.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> --- arch/x86/mm/mmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index db3165714521..196bed43d5e6 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -230,7 +230,7 @@ bool mmap_address_hint_valid(unsigned long addr, unsigned long len) /* Can we access it for direct reading/writing? Must be RAM: */ int valid_phys_addr_range(phys_addr_t addr, size_t count) { - return addr + count <= __pa(high_memory); + return addr + count <= __pa_nodebug(high_memory); } /* Can we access it through mmap? Must be a valid physical address: */ -- 2.20.1
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