• Thomas Gleixner's avatar
    [PATCH] sys_alarm() unsigned signed conversion fixup · c08b8a49
    Thomas Gleixner authored
    alarm() calls the kernel with an unsigend int timeout in seconds.  The
    value is stored in the tv_sec field of a struct timeval to setup the
    itimer.  The tv_sec field of struct timeval is of type long, which causes
    the tv_sec value to be negative on 32 bit machines if seconds > INT_MAX.
    
    Before the hrtimer merge (pre 2.6.16) such a negative value was converted
    to the maximum jiffies timeout by the timeval_to_jiffies conversion.  It's
    not clear whether this was intended or just happened to be done by the
    timeval_to_jiffies code.
    
    hrtimers expect a timeval in canonical form and treat a negative timeout as
    already expired.  This breaks the legitimate usage of alarm() with a
    timeout value > INT_MAX seconds.
    
    For 32 bit machines it is therefor necessary to limit the internal seconds
    value to avoid API breakage.  Instead of doing this in all implementations
    of sys_alarm the duplicated sys_alarm code is moved into a common function
    in itimer.c
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    c08b8a49
sysirix.c 50 KB