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    Subject[REVIEW][PATCH 02/17] sparc: fix compat siginfo ABI regression
    From: "Dmitry V. Levin" <ldv@altlinux.org>

    Starting with commit v4.14-rc1~60^2^2~1, a SIGFPE signal sent via kill
    results to wrong values in si_pid and si_uid fields of compat siginfo_t.

    This happens due to FPE_FIXME being defined to 0 for sparc, and at the
    same time siginfo_layout() introduced by the same commit returns
    SIL_FAULT for SIGFPE if si_code == SI_USER and FPE_FIXME is defined to 0.

    Fix this regression by removing FPE_FIXME macro and changing all its users
    to assign FPE_FLTUNK to si_code instead of FPE_FIXME.

    Note that FPE_FLTUNK is a new macro introduced by commit
    266da65e9156d93e1126e185259a4aae68188d0e.

    Tested with commit v4.16-11958-g16e205cf42da.

    This bug was found by strace test suite.

    In the discussion about FPE_FLTUNK on sparc David Miller said:
    > Eric, feel free to do something similar on Sparc.

    Link: https://github.com/strace/strace/issues/21
    Fixes: cc731525f26a ("signal: Remove kernel interal si_code magic")
    Fixes: 2.3.41
    Cc: David Miller <davem@davemloft.net>
    Cc: sparclinux@vger.kernel.org
    Conceptually-Acked-By: David Miller <davem@davemloft.net>
    Thanks-to: Anatoly Pugachev <matorola@gmail.com>
    Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
    Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
    ---
    arch/sparc/include/uapi/asm/siginfo.h | 7 -------
    arch/sparc/kernel/traps_32.c | 2 +-
    arch/sparc/kernel/traps_64.c | 2 +-
    3 files changed, 2 insertions(+), 9 deletions(-)

    diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h
    index 896ce447d16a..e7049550ac82 100644
    --- a/arch/sparc/include/uapi/asm/siginfo.h
    +++ b/arch/sparc/include/uapi/asm/siginfo.h
    @@ -17,13 +17,6 @@

    #define SI_NOINFO 32767 /* no information in siginfo_t */

    -/*
    - * SIGFPE si_codes
    - */
    -#ifdef __KERNEL__
    -#define FPE_FIXME 0 /* Broken dup of SI_USER */
    -#endif /* __KERNEL__ */
    -
    /*
    * SIGEMT si_codes
    */
    diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
    index b1ed763e4787..33cd35bf3dc8 100644
    --- a/arch/sparc/kernel/traps_32.c
    +++ b/arch/sparc/kernel/traps_32.c
    @@ -307,7 +307,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
    info.si_errno = 0;
    info.si_addr = (void __user *)pc;
    info.si_trapno = 0;
    - info.si_code = FPE_FIXME;
    + info.si_code = FPE_FLTUNK;
    if ((fsr & 0x1c000) == (1 << 14)) {
    if (fsr & 0x10)
    info.si_code = FPE_FLTINV;
    diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
    index 462a21abd105..e81072ac52c3 100644
    --- a/arch/sparc/kernel/traps_64.c
    +++ b/arch/sparc/kernel/traps_64.c
    @@ -2372,7 +2372,7 @@ static void do_fpe_common(struct pt_regs *regs)
    info.si_errno = 0;
    info.si_addr = (void __user *)regs->tpc;
    info.si_trapno = 0;
    - info.si_code = FPE_FIXME;
    + info.si_code = FPE_FLTUNK;
    if ((fsr & 0x1c000) == (1 << 14)) {
    if (fsr & 0x10)
    info.si_code = FPE_FLTINV;
    --
    2.14.1
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