From: "Eric W. Biederman" ebiederm@xmission.com
[ 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@samba.org Cc: Kumar Gala kumar.gala@freescale.com Cc: Michael Ellerman mpe@ellerman.id.au Cc: Benjamin Herrenschmidt benh@kernel.crashing.org 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" ebiederm@xmission.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/powerpc/include/uapi/asm/siginfo.h | 15 +++++++++++++++ arch/powerpc/kernel/traps.c | 10 +++++----- 2 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/uapi/asm/siginfo.h b/arch/powerpc/include/uapi/asm/siginfo.h index ccce3ef5cd86..9c437eaf7c21 100644 --- a/arch/powerpc/include/uapi/asm/siginfo.h +++ b/arch/powerpc/include/uapi/asm/siginfo.h @@ -17,4 +17,19 @@ #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 */ diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 0dc43f9932cf..6cc0280a8ae0 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -769,7 +769,7 @@ void unknown_exception(struct pt_regs *regs) 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); } @@ -791,7 +791,7 @@ void instruction_breakpoint_exception(struct pt_regs *regs)
void RunModeException(struct pt_regs *regs) { - _exception(SIGTRAP, regs, 0, 0); + _exception(SIGTRAP, regs, TRAP_FIXME, 0); }
void __kprobes single_step_exception(struct pt_regs *regs) @@ -826,7 +826,7 @@ static void emulate_single_step(struct pt_regs *regs)
static inline int __parse_fpscr(unsigned long fpscr) { - int ret = 0; + int ret = FPE_FIXME;
/* Invalid operation */ if ((fpscr & FPSCR_VE) && (fpscr & FPSCR_VX)) @@ -1742,7 +1742,7 @@ void SPEFloatingPointException(struct pt_regs *regs) 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); @@ -1811,7 +1811,7 @@ void SPEFloatingPointRoundException(struct pt_regs *regs) 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; } }