From: "Eric W. Biederman" ebiederm@xmission.com
[ Upstream commit b80328be53c215346b153769267b38f531d89b4f ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/metag/include/uapi/asm/siginfo.h | 7 +++++++ arch/metag/kernel/traps.c | 2 +- 2 files changed, 8 insertions(+), 1 deletion(-)
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);