From: "Darren Hart (VMware)" <[email protected]> uaddr alignment is currently tested by get_futex_key(). We can catch misalignment earlier in sys_futex and return -EINVAL sooner. This simplifies get_futex_key() a little, but more importantly exits the kernel as soon as an invalid parameter is detected.
Passes all selftests/futex testcases on a dual socket Xeon E5-2670, 16 physical cores total, 32 threads total. Signed-off-by: Darren Hart (VMware) <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Darren Hart <[email protected]> --- kernel/futex.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index 76ed592..c3ee6c4 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -509,8 +509,6 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw) * The futex address must be "naturally" aligned. */ key->both.offset = address % PAGE_SIZE; - if (unlikely((address % sizeof(u32)) != 0)) - return -EINVAL; address -= key->both.offset; if (unlikely(!access_ok(rw, uaddr, sizeof(u32)))) @@ -3525,6 +3523,11 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, u32 val2 = 0; int cmd = op & FUTEX_CMD_MASK; + /* Only allow for aligned uaddr variables */ + if (unlikely((unsigned long)uaddr % sizeof(u32) != 0 || + (unsigned long)uaddr2 % sizeof(u32) != 0)) + return -EINVAL; + if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI || cmd == FUTEX_WAIT_BITSET || cmd == FUTEX_WAIT_REQUEUE_PI)) { -- 2.9.4
