On Tue, Jul 07, 2015 at 03:22:43AM +0200, Oleg Nesterov wrote:
> 1. It doesn't make sense to continue if handle_trampoline() fails,
> change handle_swbp() to always return after this call.
>
> 2. Turn pr_warn() into uprobe_warn(), and change handle_trampoline()
> to send SIGILL on failure. It is pointless to return to user mode
> with the corrupted instruction_pointer() which we can't restore.
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> Acked-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
Acked-by: Anton Arapov <ara...@gmail.com>
> ---
> kernel/events/uprobes.c | 21 ++++++++++-----------
> 1 files changed, 10 insertions(+), 11 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index d8c702f..eabdc21 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1770,7 +1770,7 @@ handle_uretprobe_chain(struct return_instance *ri,
> struct pt_regs *regs)
> up_read(&uprobe->register_rwsem);
> }
>
> -static bool handle_trampoline(struct pt_regs *regs)
> +static void handle_trampoline(struct pt_regs *regs)
> {
> struct uprobe_task *utask;
> struct return_instance *ri;
> @@ -1778,11 +1778,11 @@ static bool handle_trampoline(struct pt_regs *regs)
>
> utask = current->utask;
> if (!utask)
> - return false;
> + goto sigill;
>
> ri = utask->return_instances;
> if (!ri)
> - return false;
> + goto sigill;
>
> /*
> * TODO: we should throw out return_instance's invalidated by
> @@ -1804,8 +1804,12 @@ static bool handle_trampoline(struct pt_regs *regs)
> }
>
> utask->return_instances = ri;
> + return;
> +
> + sigill:
> + uprobe_warn(current, "handle uretprobe, sending SIGILL.");
> + force_sig_info(SIGILL, SEND_SIG_FORCED, current);
>
> - return true;
> }
>
> bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs)
> @@ -1824,13 +1828,8 @@ static void handle_swbp(struct pt_regs *regs)
> int uninitialized_var(is_swbp);
>
> bp_vaddr = uprobe_get_swbp_addr(regs);
> - if (bp_vaddr == get_trampoline_vaddr()) {
> - if (handle_trampoline(regs))
> - return;
> -
> - pr_warn("uprobe: unable to handle uretprobe pid/tgid=%d/%d\n",
> - current->pid, current->tgid);
> - }
> + if (bp_vaddr == get_trampoline_vaddr())
> + return handle_trampoline(regs);
>
> uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
> if (!uprobe) {
> --
> 1.5.5.1
>
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