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Groups > linux.kernel > #1580390

[PATCH] kretprobes: reject registration if a symbol offset is specified

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Users shouldn't be able to specify an offset with kretprobes, as we always
want to probe at function entry. Otherwise, we won't be able to capture
the proper return address resulting in the kretprobe never firing.

With samples/kprobes/kretprobe_example.c including an offset:
	my_kretprobe.kp.offset = 40;

Before this patch, the probe gets planted but never fires.

After this patch:
	$ sudo insmod samples/kprobes/kretprobe_example.ko
	[sudo] password for naveen: 
	insmod: ERROR: could not insert module samples/kprobes/kretprobe_example.ko: Operation not permitted

And dmesg:
	[48253.757629] register_kretprobe failed, returned -22

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 kernel/kprobes.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 60a702a05684..83ad7e440417 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1847,6 +1847,9 @@ int register_kretprobe(struct kretprobe *rp)
 	int i;
 	void *addr;
 
+	if (rp->kp.offset)
+		return -EINVAL;
+
 	if (kretprobe_blacklist_size) {
 		addr = kprobe_addr(&rp->kp);
 		if (IS_ERR(addr))
-- 
2.11.0

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[PATCH] kretprobes: reject registration if a symbol offset is specified "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-14 09:40 +0100
  Re: [PATCH] kretprobes: reject registration if a symbol offset is  specified Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> - 2017-02-14 09:50 +0100
  Re: [PATCH] kretprobes: reject registration if a symbol offset is  specified Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-14 11:40 +0100
    Re: [PATCH] kretprobes: reject registration if a symbol offset is  specified "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-15 19:00 +0100
      [PATCH 3/3] perf: revert "perf probe: Fix probing kretprobes" "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-15 19:20 +0100
        Re: [PATCH 3/3] perf: revert "perf probe: Fix probing kretprobes" Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-16 00:50 +0100
      [PATCH 1/3] kretprobes: ensure probe location is at function entry "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-15 19:20 +0100
        [PATCH 2/3] trace/kprobes: allow return probes with offsets and absolute addresses "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-15 19:20 +0100
          Re: [PATCH 2/3] trace/kprobes: allow return probes with offsets and  absolute addresses Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-16 00:50 +0100
        Re: [PATCH 1/3] kretprobes: ensure probe location is at function  entry Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-16 00:50 +0100
          Re: [PATCH 1/3] kretprobes: ensure probe location is at function  entry "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-16 09:00 +0100
        [PATCH 0/2] powerpc: kretprobe updates "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-16 09:20 +0100
          [PATCH 1/2] powerpc: kretprobes: override default function entry offset "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-16 09:20 +0100
          [PATCH 2/2] perf: powerpc: choose LEP with kretprobes "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-16 09:20 +0100
          Re: [PATCH 0/2] powerpc: kretprobe updates Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-17 11:50 +0100
            Re: [PATCH 0/2] powerpc: kretprobe updates Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-02-17 21:50 +0100
              Re: [PATCH 0/2] powerpc: kretprobe updates Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-19 05:50 +0100
                Re: [PATCH 0/2] powerpc: kretprobe updates "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-20 11:00 +0100
                Re: [PATCH 0/2] powerpc: kretprobe updates Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-21 14:10 +0100
                Re: [PATCH 0/2] powerpc: kretprobe updates "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-22 14:50 +0100
              Re: [PATCH 0/2] powerpc: kretprobe updates "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-20 10:50 +0100
              Re: [PATCH 0/2] powerpc: kretprobe updates "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-20 12:50 +0100
                Re: [PATCH 0/2] powerpc: kretprobe updates Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-21 14:10 +0100
      Re: [PATCH] kretprobes: reject registration if a symbol offset is  specified Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-16 00:30 +0100

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