From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Jessica Yu <jeyu@kernel.org>
Cc: linux-kernel@vger.kernel.org, live-patching@vger.kernel.org
Subject: /proc/kallsyms shows undefined symbols for livepatch modules
Date: Sat, 2 Jun 2018 12:32:33 -0500 [thread overview]
Message-ID: <20180602173209.merjb4o5a3wsdnbh@treble> (raw)
Hi Jessica,
I found a bug:
[root@f25 ~]# modprobe livepatch-sample
[root@f25 ~]# grep ' u ' /proc/kallsyms
ffffffff81161080 u klp_enable_patch [livepatch_sample]
ffffffff81a01800 u __fentry__ [livepatch_sample]
ffffffff81161250 u klp_unregister_patch [livepatch_sample]
ffffffff81161870 u klp_register_patch [livepatch_sample]
ffffffff8131f0b0 u seq_printf [livepatch_sample]
Notice that livepatch modules' undefined symbols are showing up in
/proc/kallsyms. This can confuse klp_find_object_symbol() which can
cause subtle bugs in livepatch.
I stared at the module kallsyms code for a bit, but I don't see the bug.
Maybe it has something to do with how we save the symbol table in
copy_module_elf(). Any ideas?
--
Josh
next reply other threads:[~2018-06-02 17:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-02 17:32 Josh Poimboeuf [this message]
2018-06-04 8:05 ` Jessica Yu
2018-06-04 9:54 ` Jessica Yu
2018-06-04 13:01 ` [PATCH] module: exclude SHN_UNDEF symbols from kallsyms api Jessica Yu
2018-06-04 13:16 ` Josh Poimboeuf
2018-06-04 14:05 ` Jessica Yu
2018-06-04 14:54 ` Josh Poimboeuf
2018-06-04 22:56 ` Josh Poimboeuf
2018-06-04 23:02 ` Josh Poimboeuf
2018-06-05 7:39 ` Jessica Yu
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