This is a note to let you know that I've just added the patch titled
signal/arm: Document conflicts with SI_USER and SIGFPE
to the 4.15-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-arm-document-conflicts-with-si_user-and-sigfpe.patch
and it can be found in the queue-4.15 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 Mon Apr 9 10:16:32 CEST 2018
From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Date: Thu, 17 Aug 2017 17:07:46 -0500
Subject: signal/arm: Document conflicts with SI_USER and SIGFPE
From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
[ Upstream commit 7771c66457004977b616bab785209f49d164f527 ]
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@xxxxxxxxxxxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
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.git
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/arm/include/uapi/asm/siginfo.h | 13 +++++++++++++
arch/arm/vfp/vfpmodule.c | 2 +-
2 files changed, 14 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/include/uapi/asm/siginfo.h
--- /dev/null
+++ b/arch/arm/include/uapi/asm/siginfo.h
@@ -0,0 +1,13 @@
+#ifndef __ASM_SIGINFO_H
+#define __ASM_SIGINFO_H
+
+#include <asm-generic/siginfo.h>
+
+/*
+ * SIGFPE si_codes
+ */
+#ifdef __KERNEL__
+#define FPE_FIXME 0 /* Broken dup of SI_USER */
+#endif /* __KERNEL__ */
+
+#endif
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -257,7 +257,7 @@ static void vfp_raise_exceptions(u32 exc
if (exceptions == VFP_EXCEPTION_ERROR) {
vfp_panic("unhandled bounce", inst);
- vfp_raise_sigfpe(0, regs);
+ vfp_raise_sigfpe(FPE_FIXME, regs);
return;
}
Patches currently in stable-queue which might be from ebiederm@xxxxxxxxxxxx are
queue-4.15/signal-metag-document-a-conflict-with-si_user-with-sigfpe.patch
queue-4.15/signal-arm-document-conflicts-with-si_user-and-sigfpe.patch
queue-4.15/signal-powerpc-document-conflicts-with-si_user-and-sigfpe-and-sigtrap.patch