• Eric W. Biederman's avatar
    signal/arm: Document conflicts with SI_USER and SIGFPE · 7771c664
    Eric W. Biederman authored
    Setting si_code to 0 results in a userspace seeing an si_code of 0.
    This is the same si_code as SI_USER.  Posix and common sense requires
    that SI_USER not be a signal specific si_code.  As such this use of 0
    for the si_code is a pretty horribly broken ABI.
    
    Further use of si_code == 0 guaranteed that copy_siginfo_to_user saw a
    value of __SI_KILL and now sees a value of SIL_KILL with the result
    that uid and pid fields are copied and which might copying the si_addr
    field by accident but certainly not by design.  Making this a very
    flakey implementation.
    
    Utilizing FPE_FIXME, siginfo_layout will now return SIL_FAULT and the
    appropriate fields will be reliably copied.
    
    Possible ABI fixes includee:
    - Send the signal without siginfo
    - Don't generate a signal
    - Possibly assign and use an appropriate si_code
    - Don't handle cases which can't happen
    
    Cc: Russell King <rmk@flint.arm.linux.org.uk>
    Cc: linux-arm-kernel@lists.infradead.org
    Ref: 451436b7 ("[ARM] Add support code for ARM hardware vector floating point")
    History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.gitSigned-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
    7771c664
vfpmodule.c 20.9 KB