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Subject[tip:perf/core] uprobes: Send SIGILL if handle_trampoline() fails
Commit-ID:  0b5256c7f173258b19d98364adb57f707dda22f3
Gitweb: http://git.kernel.org/tip/0b5256c7f173258b19d98364adb57f707dda22f3
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Tue, 21 Jul 2015 15:40:08 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 31 Jul 2015 10:38:03 +0200

uprobes: Send SIGILL if handle_trampoline() fails

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.

Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134008.GA4745@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/events/uprobes.c | 21 ++++++++++-----------
1 file 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) {

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