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authorEric W. Biederman <ebiederm@xmission.com>2017-07-31 22:25:01 -0500
committerEric W. Biederman <ebiederm@xmission.com>2018-01-12 14:21:03 -0600
commitb5daf2b9d1c9a2b4f03ca93f75913ba2da3b3eaa (patch)
tree458b81054e341f824befef521db5d27c3dfbcb8e /arch/parisc/kernel/traps.c
parentsignal/openrisc: Fix do_unaligned_access to send the proper signal (diff)
downloadlinux-dev-b5daf2b9d1c9a2b4f03ca93f75913ba2da3b3eaa.tar.xz
linux-dev-b5daf2b9d1c9a2b4f03ca93f75913ba2da3b3eaa.zip
signal/parisc: Document a conflict with SI_USER with SIGFPE
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>
Diffstat (limited to 'arch/parisc/kernel/traps.c')
-rw-r--r--arch/parisc/kernel/traps.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index 8453724b8009..c919e6c0a687 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -629,7 +629,7 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
si.si_signo = SIGFPE;
/* Set to zero, and let the userspace app figure it out from
the insn pointed to by si_addr */
- si.si_code = 0;
+ si.si_code = FPE_FIXME;
si.si_addr = (void __user *) regs->iaoq[0];
force_sig_info(SIGFPE, &si, current);
return;