1. 13 1月, 2018 1 次提交
    • E
      signal/arm: Document conflicts with SI_USER and SIGFPE · 7771c664
      Eric W. Biederman 提交于
      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: 451436b7bbb2 ("[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: N"Eric W. Biederman" <ebiederm@xmission.com>
      7771c664