This is a note to let you know that I've just added the patch titled
signal/metag: Document a conflict with SI_USER with SIGFPE
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
signal-metag-document-a-conflict-with-si_user-with-sigfpe.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Apr 10 10:31:53 CEST 2018
From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Date: Tue, 1 Aug 2017 10:37:40 -0500
Subject: signal/metag: Document a conflict with SI_USER with SIGFPE
From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
[ Upstream commit b80328be53c215346b153769267b38f531d89b4f ]
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@xxxxxxxxxx>
Cc: linux-metag@xxxxxxxxxxxxxxx
Ref: ac919f0883e5 ("metag: Traps")
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/metag/include/uapi/asm/siginfo.h | 7 +++++++
arch/metag/kernel/traps.c | 2 +-
2 files changed, 8 insertions(+), 1 deletion(-)
--- a/arch/metag/include/uapi/asm/siginfo.h
+++ b/arch/metag/include/uapi/asm/siginfo.h
@@ -5,4 +5,11 @@
#include <asm-generic/siginfo.h>
+/*
+ * SIGFPE si_codes
+ */
+#ifdef __KERNEL__
+#define FPE_FIXME 0 /* Broken dup of SI_USER */
+#endif /* __KERNEL__ */
+
#endif
--- a/arch/metag/kernel/traps.c
+++ b/arch/metag/kernel/traps.c
@@ -732,7 +732,7 @@ TBIRES fpe_handler(TBIRES State, int Sig
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);
Patches currently in stable-queue which might be from ebiederm@xxxxxxxxxxxx are
queue-4.4/signal-metag-document-a-conflict-with-si_user-with-sigfpe.patch
queue-4.4/pidns-disable-pid-allocation-if-pid_ns_prepare_proc-is-failed-in-alloc_pid.patch
queue-4.4/signal-arm-document-conflicts-with-si_user-and-sigfpe.patch
queue-4.4/signal-powerpc-document-conflicts-with-si_user-and-sigfpe-and-sigtrap.patch