diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2017-08-01 10:37:40 -0500 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2018-01-12 14:21:03 -0600 |
| commit | b80328be53c215346b153769267b38f531d89b4f (patch) | |
| tree | 69f18932803d95114d187fd6b897599d2710f67d | |
| parent | b5daf2b9d1c9a2b4f03ca93f75913ba2da3b3eaa (diff) | |
signal/metag: Document a conflict with SI_USER with SIGFPE
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
hat 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 reliably be 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: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Ref: ac919f0883e5 ("metag: Traps")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| -rw-r--r-- | arch/metag/include/uapi/asm/siginfo.h | 7 | ||||
| -rw-r--r-- | arch/metag/kernel/traps.c | 2 |
2 files changed, 8 insertions, 1 deletions
diff --git a/arch/metag/include/uapi/asm/siginfo.h b/arch/metag/include/uapi/asm/siginfo.h index b54ef7186ca3..9a3f6cde9487 100644 --- a/arch/metag/include/uapi/asm/siginfo.h +++ b/arch/metag/include/uapi/asm/siginfo.h @@ -6,4 +6,11 @@ #include <asm-generic/siginfo.h> +/* + * SIGFPE si_codes + */ +#ifdef __KERNEL__ +#define FPE_FIXME 0 /* Broken dup of SI_USER */ +#endif /* __KERNEL__ */ + #endif diff --git a/arch/metag/kernel/traps.c b/arch/metag/kernel/traps.c index 444851e510d5..3b62b1b0c0b5 100644 --- a/arch/metag/kernel/traps.c +++ b/arch/metag/kernel/traps.c @@ -735,7 +735,7 @@ TBIRES fpe_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI) else if (error_state & TXSTAT_FPE_INEXACT_BIT) info.si_code = FPE_FLTRES; else - info.si_code = 0; + info.si_code = FPE_FIXME; info.si_errno = 0; info.si_addr = (__force void __user *)regs->ctx.CurrPC; force_sig_info(SIGFPE, &info, current); |