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authorEric W. Biederman <ebiederm@xmission.com>2017-08-01 10:37:40 -0500
committerEric W. Biederman <ebiederm@xmission.com>2018-01-12 14:21:03 -0600
commitb80328be53c215346b153769267b38f531d89b4f (patch)
tree69f18932803d95114d187fd6b897599d2710f67d
parentb5daf2b9d1c9a2b4f03ca93f75913ba2da3b3eaa (diff)
signal/metag: 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 hat 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. 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 Hogan <james.hogan@imgtec.com> Cc: linux-metag@vger.kernel.org Ref: ac919f0883e5 ("metag: Traps") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
-rw-r--r--arch/metag/include/uapi/asm/siginfo.h7
-rw-r--r--arch/metag/kernel/traps.c2
2 files changed, 8 insertions, 1 deletions
diff --git a/arch/metag/include/uapi/asm/siginfo.h b/arch/metag/include/uapi/asm/siginfo.h
index b54ef7186ca3..9a3f6cde9487 100644
--- a/arch/metag/include/uapi/asm/siginfo.h
+++ b/arch/metag/include/uapi/asm/siginfo.h
@@ -6,4 +6,11 @@
#include <asm-generic/siginfo.h>
+/*
+ * SIGFPE si_codes
+ */
+#ifdef __KERNEL__
+#define FPE_FIXME 0 /* Broken dup of SI_USER */
+#endif /* __KERNEL__ */
+
#endif
diff --git a/arch/metag/kernel/traps.c b/arch/metag/kernel/traps.c
index 444851e510d5..3b62b1b0c0b5 100644
--- a/arch/metag/kernel/traps.c
+++ b/arch/metag/kernel/traps.c
@@ -735,7 +735,7 @@ TBIRES fpe_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI)
else if (error_state & TXSTAT_FPE_INEXACT_BIT)
info.si_code = FPE_FLTRES;
else
- info.si_code = 0;
+ info.si_code = FPE_FIXME;
info.si_errno = 0;
info.si_addr = (__force void __user *)regs->ctx.CurrPC;
force_sig_info(SIGFPE, &info, current);