<gregkh@xxxxxxxxxxxxxxxxxxx> 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 <stable@xxxxxxxxxxxxxxx> 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" <ebiederm@xxxxxxxxxxxx> > 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" <ebiederm@xxxxxxxxxxxx> > > > [ 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 <paulus@xxxxxxxxx> > Cc: Kumar Gala <kumar.gala@xxxxxxxxxxxxx> > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > Cc: linuxppc-dev@xxxxxxxxxxxxxxxx > 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" <ebiederm@xxxxxxxxxxxx> > Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > --- > 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@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