From dcecb8fd93a65787130a74e61fdf29932c8d85eb Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Thu, 31 Jul 2014 16:22:25 +0100 Subject: [PATCH] xen/events/fifo: ensure all bitops are properly aligned even on x86 When using the FIFO-based ABI on x86_64, if the last port is at the end of an event array page then sync_test_bit() on this port's event word will read beyond the end of the page and in certain circumstances this may fault. The fault requires the following page in the kernel's direct mapping to be not present, which would mean: a) the array page is the last page of RAM; or b) the following page is ballooned out /and/ it has been used for a foreign mapping by a kernel driver (such as netback or blkback) /and/ the grant has been unmapped. Use the infrastructure added for arm64 to ensure that all bitops operating on event words are unsigned long aligned. Signed-off-by: David Vrabel Reviewed-by: Boris Ostrovsky Cc: stable@vger.kernel.org --- drivers/xen/events/events_fifo.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c index c7ff2035b98e..48dcb2e97b90 100644 --- a/drivers/xen/events/events_fifo.c +++ b/drivers/xen/events/events_fifo.c @@ -67,10 +67,9 @@ static event_word_t *event_array[MAX_EVENT_ARRAY_PAGES] __read_mostly; static unsigned event_array_pages __read_mostly; /* - * sync_set_bit() and friends must be unsigned long aligned on non-x86 - * platforms. + * sync_set_bit() and friends must be unsigned long aligned. */ -#if !defined(CONFIG_X86) && BITS_PER_LONG > 32 +#if BITS_PER_LONG > 32 #define BM(w) (unsigned long *)((unsigned long)w & ~0x7UL) #define EVTCHN_FIFO_BIT(b, w) \ -- 2.11.0