5.0-stable review patch. If anyone has any objections, please let me know.
------------------ From: Chen Jie <[email protected]> commit 5a07168d8d89b00fe1760120714378175b3ef992 upstream. The futex code requires that the user space addresses of futexes are 32bit aligned. sys_futex() checks this in futex_get_keys() but the robust list code has no alignment check in place. As a consequence the kernel crashes on architectures with strict alignment requirements in handle_futex_death() when trying to cmpxchg() on an unaligned futex address which was retrieved from the robust list. [ tglx: Rewrote changelog, proper sizeof() based alignement check and add comment ] Fixes: 0771dfefc9e5 ("[PATCH] lightweight robust futexes: core") Signed-off-by: Chen Jie <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]> --- kernel/futex.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/kernel/futex.c +++ b/kernel/futex.c @@ -3440,6 +3440,10 @@ static int handle_futex_death(u32 __user { u32 uval, uninitialized_var(nval), mval; + /* Futex address must be 32bit aligned */ + if ((((unsigned long)uaddr) % sizeof(*uaddr)) != 0) + return -1; + retry: if (get_user(uval, uaddr)) return -1;
