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tracing: Fix bad use of igrab in trace_uprobe.c
commit0c92c7a3c5
upstream. As Miklos reported and suggested: This pattern repeats two times in trace_uprobe.c and in kernel/events/core.c as well: ret = kern_path(filename, LOOKUP_FOLLOW, &path); if (ret) goto fail_address_parse; inode = igrab(d_inode(path.dentry)); path_put(&path); And it's wrong. You can only hold a reference to the inode if you have an active ref to the superblock as well (which is normally through path.mnt) or holding s_umount. This way unmounting the containing filesystem while the tracepoint is active will give you the "VFS: Busy inodes after unmount..." message and a crash when the inode is finally put. Solution: store path instead of inode. This patch fixes two instances in trace_uprobe.c. struct path is added to struct trace_uprobe to keep the inode and containing mount point referenced. Link: http://lkml.kernel.org/r/20180423172135.4050588-1-songliubraving@fb.com Fixes:f3f096cfed
("tracing: Provide trace events interface for uprobes") Fixes:33ea4b2427
("perf/core: Implement the 'perf_uprobe' PMU") Cc: stable@vger.kernel.org Cc: Ingo Molnar <mingo@redhat.com> Cc: Howard McLauchlan <hmclauchlan@fb.com> Cc: Josef Bacik <jbacik@fb.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Miklos Szeredi <mszeredi@redhat.com> Reported-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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parent
d86aaca9ce
commit
27f29dbceb
1 changed files with 10 additions and 14 deletions
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@ -55,6 +55,7 @@ struct trace_uprobe {
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struct list_head list;
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struct trace_uprobe_filter filter;
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struct uprobe_consumer consumer;
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struct path path;
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struct inode *inode;
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char *filename;
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unsigned long offset;
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@ -287,7 +288,7 @@ static void free_trace_uprobe(struct trace_uprobe *tu)
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for (i = 0; i < tu->tp.nr_args; i++)
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traceprobe_free_probe_arg(&tu->tp.args[i]);
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iput(tu->inode);
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path_put(&tu->path);
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kfree(tu->tp.call.class->system);
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kfree(tu->tp.call.name);
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kfree(tu->filename);
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@ -361,7 +362,6 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
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static int create_trace_uprobe(int argc, char **argv)
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{
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struct trace_uprobe *tu;
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struct inode *inode;
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char *arg, *event, *group, *filename;
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char buf[MAX_EVENT_NAME_LEN];
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struct path path;
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@ -369,7 +369,6 @@ static int create_trace_uprobe(int argc, char **argv)
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bool is_delete, is_return;
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int i, ret;
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inode = NULL;
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ret = 0;
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is_delete = false;
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is_return = false;
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@ -435,21 +434,16 @@ static int create_trace_uprobe(int argc, char **argv)
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}
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/* Find the last occurrence, in case the path contains ':' too. */
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arg = strrchr(argv[1], ':');
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if (!arg) {
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ret = -EINVAL;
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goto fail_address_parse;
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}
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if (!arg)
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return -EINVAL;
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*arg++ = '\0';
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filename = argv[1];
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ret = kern_path(filename, LOOKUP_FOLLOW, &path);
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if (ret)
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goto fail_address_parse;
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return ret;
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inode = igrab(d_inode(path.dentry));
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path_put(&path);
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if (!inode || !S_ISREG(inode->i_mode)) {
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if (!d_is_reg(path.dentry)) {
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ret = -EINVAL;
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goto fail_address_parse;
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}
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@ -488,7 +482,7 @@ static int create_trace_uprobe(int argc, char **argv)
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goto fail_address_parse;
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}
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tu->offset = offset;
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tu->inode = inode;
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tu->path = path;
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tu->filename = kstrdup(filename, GFP_KERNEL);
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if (!tu->filename) {
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@ -556,7 +550,7 @@ static int create_trace_uprobe(int argc, char **argv)
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return ret;
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fail_address_parse:
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iput(inode);
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path_put(&path);
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pr_info("Failed to parse address or file.\n");
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@ -935,6 +929,7 @@ probe_event_enable(struct trace_uprobe *tu, struct trace_event_file *file,
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goto err_flags;
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tu->consumer.filter = filter;
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tu->inode = d_real_inode(tu->path.dentry);
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ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
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if (ret)
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goto err_buffer;
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@ -980,6 +975,7 @@ probe_event_disable(struct trace_uprobe *tu, struct trace_event_file *file)
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WARN_ON(!uprobe_filter_is_empty(&tu->filter));
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uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
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tu->inode = NULL;
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tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
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uprobe_buffer_disable();
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