From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out03.mta.xmission.com ([166.70.13.233]:53281 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753459AbeDJOqe (ORCPT ); Tue, 10 Apr 2018 10:46:34 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Cc: alexander.levin@microsoft.com, benh@kernel.crashing.org, kumar.gala@freescale.com, mpe@ellerman.id.au, paulus@samba.org, , References: <1523266614250228@kroah.com> Date: Tue, 10 Apr 2018 09:45:14 -0500 In-Reply-To: <1523266614250228@kroah.com> (gregkh@linuxfoundation.org's message of "Mon, 09 Apr 2018 11:36:54 +0200") Message-ID: <87d0z7w26d.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: Patch "signal/powerpc: Document conflicts with SI_USER and SIGFPE and SIGTRAP" has been added to the 4.15-stable tree Sender: stable-owner@vger.kernel.org List-ID: writes: > This is a note to let you know that I've just added the patch titled > > signal/powerpc: Document conflicts with SI_USER and SIGFPE and SIGTRAP > > 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-powerpc-document-conflicts-with-si_user-and-sigfpe-and-sigtrap.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 know about it. The patch is a noop functionality wise so I don't see the point of backporting it to stable. Eric > From foo@baz Mon Apr 9 10:16:32 CEST 2018 > From: "Eric W. Biederman" > Date: Sat, 19 Aug 2017 15:26:01 -0500 > Subject: signal/powerpc: Document conflicts with SI_USER and SIGFPE and SIGTRAP > > From: "Eric W. Biederman" > > > [ Upstream commit cf4674c46c66e45f238f8f7e81af2a444b970c0a ] > > 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 and TRAP_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: Paul Mackerras > Cc: Kumar Gala > Cc: Michael Ellerman > Cc: Benjamin Herrenschmidt > Cc: linuxppc-dev@lists.ozlabs.org > Ref: 9bad068c24d7 ("[PATCH] ppc32: support for e500 and 85xx") > Ref: 0ed70f6105ef ("PPC32: Provide proper siginfo information on various exceptions.") > History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git > Signed-off-by: "Eric W. Biederman" > Signed-off-by: Sasha Levin > Signed-off-by: Greg Kroah-Hartman > --- > arch/powerpc/include/uapi/asm/siginfo.h | 15 +++++++++++++++ > arch/powerpc/kernel/traps.c | 10 +++++----- > 2 files changed, 20 insertions(+), 5 deletions(-) > > --- a/arch/powerpc/include/uapi/asm/siginfo.h > +++ b/arch/powerpc/include/uapi/asm/siginfo.h > @@ -18,4 +18,19 @@ > #undef NSIGTRAP > #define NSIGTRAP 4 > > +/* > + * SIGFPE si_codes > + */ > +#ifdef __KERNEL__ > +#define FPE_FIXME 0 /* Broken dup of SI_USER */ > +#endif /* __KERNEL__ */ > + > +/* > + * SIGTRAP si_codes > + */ > +#ifdef __KERNEL__ > +#define TRAP_FIXME 0 /* Broken dup of SI_USER */ > +#endif /* __KERNEL__ */ > + > + > #endif /* _ASM_POWERPC_SIGINFO_H */ > --- a/arch/powerpc/kernel/traps.c > +++ b/arch/powerpc/kernel/traps.c > @@ -917,7 +917,7 @@ void unknown_exception(struct pt_regs *r > printk("Bad trap at PC: %lx, SR: %lx, vector=%lx\n", > regs->nip, regs->msr, regs->trap); > > - _exception(SIGTRAP, regs, 0, 0); > + _exception(SIGTRAP, regs, TRAP_FIXME, 0); > > exception_exit(prev_state); > } > @@ -939,7 +939,7 @@ bail: > > void RunModeException(struct pt_regs *regs) > { > - _exception(SIGTRAP, regs, 0, 0); > + _exception(SIGTRAP, regs, TRAP_FIXME, 0); > } > > void single_step_exception(struct pt_regs *regs) > @@ -978,7 +978,7 @@ static void emulate_single_step(struct p > > static inline int __parse_fpscr(unsigned long fpscr) > { > - int ret = 0; > + int ret = FPE_FIXME; > > /* Invalid operation */ > if ((fpscr & FPSCR_VE) && (fpscr & FPSCR_VX)) > @@ -1929,7 +1929,7 @@ void SPEFloatingPointException(struct pt > extern int do_spe_mathemu(struct pt_regs *regs); > unsigned long spefscr; > int fpexc_mode; > - int code = 0; > + int code = FPE_FIXME; > int err; > > flush_spe_to_thread(current); > @@ -1998,7 +1998,7 @@ void SPEFloatingPointRoundException(stru > printk(KERN_ERR "unrecognized spe instruction " > "in %s at %lx\n", current->comm, regs->nip); > } else { > - _exception(SIGFPE, regs, 0, regs->nip); > + _exception(SIGFPE, regs, FPE_FIXME, regs->nip); > return; > } > } > > > Patches currently in stable-queue which might be from ebiederm@xmission.com 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