[GIT PULL] tracing: Avoid memory leak in predicate_parse()

From: Steven Rostedt
Date: Tue May 28 2019 - 23:02:03 EST



Linus,

This fixes a memory leak from the error path in the event filter logic.


Please pull the latest trace-v5.2-rc2 tree, which can be found at:


git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-v5.2-rc2

Tag SHA1: 0658b13d1bfd40bda1c2bd1ef3738857e1bf4000
Head SHA1: dfb4a6f2191a80c8b790117d0ff592fd712d3296


Tomas Bortoli (1):
tracing: Avoid memory leak in predicate_parse()

----
kernel/trace/trace_events_filter.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
---------------------------
commit dfb4a6f2191a80c8b790117d0ff592fd712d3296
Author: Tomas Bortoli <tomasbortoli@xxxxxxxxx>
Date: Tue May 28 17:43:38 2019 +0200

tracing: Avoid memory leak in predicate_parse()

In case of errors, predicate_parse() goes to the out_free label
to free memory and to return an error code.

However, predicate_parse() does not free the predicates of the
temporary prog_stack array, thence leaking them.

Link: http://lkml.kernel.org/r/20190528154338.29976-1-tomasbortoli@xxxxxxxxx

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 80765597bc587 ("tracing: Rewrite filter logic to be simpler and faster")
Reported-by: syzbot+6b8e0fb820e570c59e19@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Tomas Bortoli <tomasbortoli@xxxxxxxxx>
[ Added protection around freeing prog_stack[i].pred ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index d3e59312ef40..5079d1db3754 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -428,7 +428,7 @@ predicate_parse(const char *str, int nr_parens, int nr_preds,
op_stack = kmalloc_array(nr_parens, sizeof(*op_stack), GFP_KERNEL);
if (!op_stack)
return ERR_PTR(-ENOMEM);
- prog_stack = kmalloc_array(nr_preds, sizeof(*prog_stack), GFP_KERNEL);
+ prog_stack = kcalloc(nr_preds, sizeof(*prog_stack), GFP_KERNEL);
if (!prog_stack) {
parse_error(pe, -ENOMEM, 0);
goto out_free;
@@ -579,7 +579,11 @@ predicate_parse(const char *str, int nr_parens, int nr_preds,
out_free:
kfree(op_stack);
kfree(inverts);
- kfree(prog_stack);
+ if (prog_stack) {
+ for (i = 0; prog_stack[i].pred; i++)
+ kfree(prog_stack[i].pred);
+ kfree(prog_stack);
+ }
return ERR_PTR(ret);
}