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 reliably be copied.
This bug is 13 years old and parsic machines are no longer being built
so I don't know if it possible or worth fixing it. But it is at least
worth documenting this so other architectures don't make the same
mistake.
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: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-parisc@vger.kernel.org
Ref: 313c01d3e3fd ("[PATCH] PA-RISC update for 2.6.0")
Histroy Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
b5daf2b9d1