From: "guillaume at morinfr dot org" <sourceware-bugzilla@sourceware.org>
To: systemtap@sourceware.org
Subject: [Bug tapsets/26184] fullpath_struct_file does not handle struct dentry on 5.6.19-300.fc32.x86_64
Date: Wed, 26 May 2021 22:06:21 +0000 [thread overview]
Message-ID: <bug-26184-6586-sfLrvlt9P6@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-26184-6586@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=26184
--- Comment #5 from Guillaume Morin <guillaume at morinfr dot org> ---
This appears to be still present in systemtap 4.5.
This simple workaround seems to fix the problem:
--- a/tapset/linux/dentry.stp 2021-05-26 17:44:48.283925000 -0400
+++ b/tapset/linux/dentry.stp 2021-05-26 17:44:59.122807962 -0400
@@ -264,7 +264,7 @@
/* RHEL7+ kernels */
if (! @type_member_defined("vfsmount", mnt_parent)) {
/* Global root? */
- if (mnt != mnt->mnt_parent) {
+ if (mnt && mnt != mnt->mnt_parent) {
dentry = mnt->mnt_mountpoint
vfsmnt = & mnt->mnt_parent->mnt
mnt = mnt->mnt_parent
However, mnt should not be 0 at that point in the code. The mnt var should be
defined if @type_member_defined("mount", mnt_parent) is true and it should be
the case in any kernel released in the past 10 years.
_But_ I verified that it does not evaluate to true with the example given by
the original reporter (stap -v -c /bin/false -e 'probe process.begin {
printf("%s\n", fullpath_struct_file(task_current(), current_exe_file()));
exit(); }').
I also can reproduce with a completely different example (a longer one). I
could provide it if necessary but the original reproducer is simple enough.
It does look like a bug similar to
https://sourceware.org/bugzilla/show_bug.cgi?id=20672
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next prev parent reply other threads:[~2021-05-26 22:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-26 21:26 [Bug tapsets/26184] New: " guillaume at morinfr dot org
2021-05-26 22:06 ` guillaume at morinfr dot org [this message]
2022-03-22 18:15 ` [Bug tapsets/26184] " wcohen at redhat dot com
-- strict thread matches above, loose matches on Subject: below --
2020-07-13 6:48 Craig Ringer
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