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 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: signal-arm-document-conflicts-with-si_user-and-sigfpe.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Tue Apr 10 10:31:53 CEST 2018
From: "Eric W. Biederman" ebiederm@xmission.com Date: Thu, 17 Aug 2017 17:07:46 -0500 Subject: signal/arm: Document conflicts with SI_USER and SIGFPE
From: "Eric W. Biederman" ebiederm@xmission.com
[ 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@flint.arm.linux.org.uk Cc: linux-arm-kernel@lists.infradead.org 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@xmission.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -261,7 +261,7 @@ 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@xmission.com 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