diff options
author | Steven Rostedt <srostedt@redhat.com> | 2009-03-21 07:44:50 +0100 |
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committer | Steven Rostedt <srostedt@redhat.com> | 2009-03-24 14:07:35 +0100 |
commit | 098335215a4921a8a54193829eaed602dca24df5 (patch) | |
tree | 86226d7e4229f00e467b5e6ed7f048a2061c3042 /kernel/trace/trace_stat.c | |
parent | tracing: Fix TRACING_SUPPORT dependency for PPC32 (diff) | |
download | linux-098335215a4921a8a54193829eaed602dca24df5.tar.xz linux-098335215a4921a8a54193829eaed602dca24df5.zip |
tracing: fix memory leak in trace_stat
If the function profiler does not have any items recorded and one were
to cat the function stat file, the kernel would take a BUG with a NULL
pointer dereference.
Looking further into this, I found that returning NULL from stat_start
did not stop the stat logic, and would later call stat_next. This breaks
from the way seq_file works, so I looked into fixing the stat code.
This is where I noticed that the last next_entry is never freed.
It is allocated, and if the stat_next returns NULL, the code breaks out
of the loop, unlocks the mutex and exits. We never link the next_entry
nor do we free it. Thus it is a real memory leak.
This patch rearranges the code a bit to not only fix the memory leak,
but also to act more like seq_file where nothing is printed if there
is nothing to print. That is, stat_start returns NULL.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Diffstat (limited to 'kernel/trace/trace_stat.c')
-rw-r--r-- | kernel/trace/trace_stat.c | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c index 39310e3434ee..f71b85b22cfe 100644 --- a/kernel/trace/trace_stat.c +++ b/kernel/trace/trace_stat.c @@ -75,7 +75,7 @@ static int stat_seq_init(struct tracer_stat_session *session) { struct trace_stat_list *iter_entry, *new_entry; struct tracer_stat *ts = session->ts; - void *prev_stat; + void *stat; int ret = 0; int i; @@ -85,6 +85,10 @@ static int stat_seq_init(struct tracer_stat_session *session) if (!ts->stat_cmp) ts->stat_cmp = dummy_cmp; + stat = ts->stat_start(); + if (!stat) + goto exit; + /* * The first entry. Actually this is the second, but the first * one (the stat_list head) is pointless. @@ -99,14 +103,19 @@ static int stat_seq_init(struct tracer_stat_session *session) list_add(&new_entry->list, &session->stat_list); - new_entry->stat = ts->stat_start(); - prev_stat = new_entry->stat; + new_entry->stat = stat; /* * Iterate over the tracer stat entries and store them in a sorted * list. */ for (i = 1; ; i++) { + stat = ts->stat_next(stat, i); + + /* End of insertion */ + if (!stat) + break; + new_entry = kmalloc(sizeof(struct trace_stat_list), GFP_KERNEL); if (!new_entry) { ret = -ENOMEM; @@ -114,11 +123,7 @@ static int stat_seq_init(struct tracer_stat_session *session) } INIT_LIST_HEAD(&new_entry->list); - new_entry->stat = ts->stat_next(prev_stat, i); - - /* End of insertion */ - if (!new_entry->stat) - break; + new_entry->stat = stat; list_for_each_entry(iter_entry, &session->stat_list, list) { @@ -137,8 +142,6 @@ static int stat_seq_init(struct tracer_stat_session *session) break; } } - - prev_stat = new_entry->stat; } exit: mutex_unlock(&session->stat_mutex); |