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    Subject[PATCH AUTOSEL 4.19 132/205] signal: Properly deliver SIGILL from uprobes
    Date
    From: "Eric W. Biederman" <ebiederm@xmission.com>

    [ Upstream commit 55a3235fc71bf34303e34a95eeee235b2d2a35dd ]

    For userspace to tell the difference between a random signal and an
    exception, the exception must include siginfo information.

    Using SEND_SIG_FORCED for SIGILL is thus wrong, and it will result
    in userspace seeing si_code == SI_USER (like a random signal) instead
    of si_code == SI_KERNEL or a more specific si_code as all exceptions
    deliver.

    Therefore replace force_sig_info(SIGILL, SEND_SIG_FORCE, current)
    with force_sig(SIG_ILL, current) which gets this right and is
    shorter and easier to type.

    Fixes: 014940bad8e4 ("uprobes/x86: Send SIGILL if arch_uprobe_post_xol() fails")
    Fixes: 0b5256c7f173 ("uprobes: Send SIGILL if handle_trampoline() fails")
    Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/events/uprobes.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
    index 578d4ac54484f..c173e4131df88 100644
    --- a/kernel/events/uprobes.c
    +++ b/kernel/events/uprobes.c
    @@ -1858,7 +1858,7 @@ static void handle_trampoline(struct pt_regs *regs)

    sigill:
    uprobe_warn(current, "handle uretprobe, sending SIGILL.");
    - force_sig_info(SIGILL, SEND_SIG_FORCED, current);
    + force_sig(SIGILL, current);

    }

    @@ -1974,7 +1974,7 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)

    if (unlikely(err)) {
    uprobe_warn(current, "execute the probed insn, sending SIGILL.");
    - force_sig_info(SIGILL, SEND_SIG_FORCED, current);
    + force_sig(SIGILL, current);
    }
    }

    --
    2.20.1
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