> On Apr 18, 2018, at 10:47 AM, Steven Rostedt <[email protected]> wrote: > > You forgot to add Miklos again. >
I am really sorry! I was expecting "Reported-by" to add Miklos. Song > Miklos, have any comments on this patch? Or can you give a > "Reviewed-by"? > > -- Steve > > > On Wed, 18 Apr 2018 10:40:14 -0700 > Song Liu <[email protected]> wrote: > >> 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. >> >> Fixes: f3f096cfedf8 ("tracing: Provide trace events interface for uprobes") >> Fixes: 33ea4b24277b ("perf/core: Implement the 'perf_uprobe' PMU") >> Cc: Steven Rostedt <[email protected]> >> Cc: Ingo Molnar <[email protected]> >> Cc: Howard McLauchlan <[email protected]> >> Cc: Josef Bacik <[email protected]> >> Cc: Srikar Dronamraju <[email protected]> >> Reported-by: Miklos Szeredi <[email protected]> >> Signed-off-by: Song Liu <[email protected]> >> --- >> kernel/trace/trace_uprobe.c | 49 >> +++++++++++++++------------------------------ >> 1 file changed, 16 insertions(+), 33 deletions(-) >> >> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c >> index 34fd0e0..d9ee522c 100644 >> --- a/kernel/trace/trace_uprobe.c >> +++ b/kernel/trace/trace_uprobe.c >> @@ -55,7 +55,7 @@ struct trace_uprobe { >> struct list_head list; >> struct trace_uprobe_filter filter; >> struct uprobe_consumer consumer; >> - struct inode *inode; >> + struct path path; >> char *filename; >> unsigned long offset; >> unsigned long nhit; >> @@ -289,7 +289,7 @@ static void free_trace_uprobe(struct trace_uprobe *tu) >> for (i = 0; i < tu->tp.nr_args; i++) >> traceprobe_free_probe_arg(&tu->tp.args[i]); >> >> - iput(tu->inode); >> + path_put(&tu->path); >> kfree(tu->tp.call.class->system); >> kfree(tu->tp.call.name); >> kfree(tu->filename); >> @@ -363,7 +363,6 @@ static int register_trace_uprobe(struct trace_uprobe *tu) >> static int create_trace_uprobe(int argc, char **argv) >> { >> struct trace_uprobe *tu; >> - struct inode *inode; >> char *arg, *event, *group, *filename; >> char buf[MAX_EVENT_NAME_LEN]; >> struct path path; >> @@ -371,7 +370,6 @@ static int create_trace_uprobe(int argc, char **argv) >> bool is_delete, is_return; >> int i, ret; >> >> - inode = NULL; >> ret = 0; >> is_delete = false; >> is_return = false; >> @@ -437,24 +435,14 @@ static int create_trace_uprobe(int argc, char **argv) >> } >> /* Find the last occurrence, in case the path contains ':' too. */ >> arg = strrchr(argv[1], ':'); >> - if (!arg) { >> - ret = -EINVAL; >> - goto fail_address_parse; >> - } >> + if (!arg) >> + return -EINVAL; >> >> *arg++ = '\0'; >> filename = argv[1]; >> ret = kern_path(filename, LOOKUP_FOLLOW, &path); >> if (ret) >> - goto fail_address_parse; >> - >> - inode = igrab(d_real_inode(path.dentry)); >> - path_put(&path); >> - >> - if (!inode || !S_ISREG(inode->i_mode)) { >> - ret = -EINVAL; >> - goto fail_address_parse; >> - } >> + return ret; >> >> ret = kstrtoul(arg, 0, &offset); >> if (ret) >> @@ -490,7 +478,7 @@ static int create_trace_uprobe(int argc, char **argv) >> goto fail_address_parse; >> } >> tu->offset = offset; >> - tu->inode = inode; >> + tu->path = path; >> tu->filename = kstrdup(filename, GFP_KERNEL); >> >> if (!tu->filename) { >> @@ -558,7 +546,7 @@ static int create_trace_uprobe(int argc, char **argv) >> return ret; >> >> fail_address_parse: >> - iput(inode); >> + path_put(&path); >> >> pr_info("Failed to parse address or file.\n"); >> >> @@ -922,7 +910,8 @@ probe_event_enable(struct trace_uprobe *tu, struct >> trace_event_file *file, >> goto err_flags; >> >> tu->consumer.filter = filter; >> - ret = uprobe_register(tu->inode, tu->offset, &tu->consumer); >> + ret = uprobe_register(d_inode(tu->path.dentry), tu->offset, >> + &tu->consumer); >> if (ret) >> goto err_buffer; >> >> @@ -966,7 +955,7 @@ probe_event_disable(struct trace_uprobe *tu, struct >> trace_event_file *file) >> >> WARN_ON(!uprobe_filter_is_empty(&tu->filter)); >> >> - uprobe_unregister(tu->inode, tu->offset, &tu->consumer); >> + uprobe_unregister(d_inode(tu->path.dentry), tu->offset, &tu->consumer); >> tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE; >> >> uprobe_buffer_disable(); >> @@ -1041,7 +1030,8 @@ static int uprobe_perf_close(struct trace_uprobe *tu, >> struct perf_event *event) >> write_unlock(&tu->filter.rwlock); >> >> if (!done) >> - return uprobe_apply(tu->inode, tu->offset, &tu->consumer, >> false); >> + return uprobe_apply(d_inode(tu->path.dentry), tu->offset, >> + &tu->consumer, false); >> >> return 0; >> } >> @@ -1073,7 +1063,8 @@ static int uprobe_perf_open(struct trace_uprobe *tu, >> struct perf_event *event) >> >> err = 0; >> if (!done) { >> - err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true); >> + err = uprobe_apply(d_inode(tu->path.dentry), >> + tu->offset, &tu->consumer, true); >> if (err) >> uprobe_perf_close(tu, event); >> } >> @@ -1337,7 +1328,6 @@ struct trace_event_call * >> create_local_trace_uprobe(char *name, unsigned long offs, bool is_return) >> { >> struct trace_uprobe *tu; >> - struct inode *inode; >> struct path path; >> int ret; >> >> @@ -1345,14 +1335,6 @@ create_local_trace_uprobe(char *name, unsigned long >> offs, bool is_return) >> if (ret) >> return ERR_PTR(ret); >> >> - inode = igrab(d_inode(path.dentry)); >> - path_put(&path); >> - >> - if (!inode || !S_ISREG(inode->i_mode)) { >> - iput(inode); >> - return ERR_PTR(-EINVAL); >> - } >> - >> /* >> * local trace_kprobes are not added to probe_list, so they are never >> * searched in find_trace_kprobe(). Therefore, there is no concern of >> @@ -1364,11 +1346,12 @@ create_local_trace_uprobe(char *name, unsigned long >> offs, bool is_return) >> if (IS_ERR(tu)) { >> pr_info("Failed to allocate trace_uprobe.(%d)\n", >> (int)PTR_ERR(tu)); >> + path_put(&path); >> return ERR_CAST(tu); >> } >> >> tu->offset = offs; >> - tu->inode = inode; >> + tu->path = path; >> tu->filename = kstrdup(name, GFP_KERNEL); >> init_trace_event_call(tu, &tu->tp.call); >> >
