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Subject[PATCH] tracepoints: prevents null probe from being added
Date
From: Sahara <keun-o.park@windriver.com>

Somehow tracepoint_entry_add/remove_probe functions allow a null probe
function. Especially on getting a null probe in remove function, it seems
to be used to remove all probe functions in the entry.
But, the code is not handled as expected. Since the tracepoint_entry
maintains funcs array's last func as NULL in order to mark it as the end
of the array. Also NULL func is used in for-loop to check out the end of
the loop. So if there's NULL func in the entry's funcs, the for-loop
will be abruptly ended in the middle of operation.
Also checking out if probe is null in for-loop is not efficient.

Signed-off-by: Sahara <keun-o.park@windriver.com>
---
kernel/tracepoint.c | 18 ++++++++++++------
1 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 0c05a45..30f427e 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -112,7 +112,10 @@ tracepoint_entry_add_probe(struct tracepoint_entry *entry,
int nr_probes = 0;
struct tracepoint_func *old, *new;

- WARN_ON(!probe);
+ if (unlikely(!probe)) {
+ WARN_ON(!probe);
+ return ERR_PTR(-EINVAL);
+ }

debug_print_probes(entry);
old = entry->funcs;
@@ -147,15 +150,19 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry,

old = entry->funcs;

+ if (unlikely(!probe)) {
+ WARN_ON(!probe);
+ return ERR_PTR(-EINVAL);
+ }
+
if (!old)
return ERR_PTR(-ENOENT);

debug_print_probes(entry);
/* (N -> M), (N > 1, M >= 0) probes */
for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
- if (!probe ||
- (old[nr_probes].func == probe &&
- old[nr_probes].data == data))
+ if (old[nr_probes].func == probe &&
+ old[nr_probes].data == data)
nr_del++;
}

@@ -173,8 +180,7 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
if (new == NULL)
return ERR_PTR(-ENOMEM);
for (i = 0; old[i].func; i++)
- if (probe &&
- (old[i].func != probe || old[i].data != data))
+ if (old[i].func != probe || old[i].data != data)
new[j++] = old[i];
new[nr_probes - nr_del].func = NULL;
entry->refcount = nr_probes - nr_del;
--
1.7.1


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