On Tue, 28 May 2019 17:43:38 +0200 Tomas Bortoli <tomasbort...@gmail.com> wrote:
> @@ -578,6 +578,8 @@ predicate_parse(const char *str, int nr_parens, int > nr_preds, > out_free: > kfree(op_stack); > kfree(inverts); > + for (i = 0; prog_stack[i].pred; i++) > + kfree(prog_stack[i].pred); > kfree(prog_stack); > return ERR_PTR(ret); > } I should have caught this, but thanks to the zero day bot, it found it first: kernel/trace/trace_events_filter.c:582:27-31: ERROR: prog_stack is NULL but dereferenced. I changed the patch with the following: >From dfb4a6f2191a80c8b790117d0ff592fd712d3296 Mon Sep 17 00:00:00 2001 From: Tomas Bortoli <tomasbort...@gmail.com> Date: Tue, 28 May 2019 17:43:38 +0200 Subject: [PATCH] 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-tomasbort...@gmail.com Cc: sta...@vger.kernel.org Fixes: 80765597bc587 ("tracing: Rewrite filter logic to be simpler and faster") Reported-by: syzbot+6b8e0fb820e570c59...@syzkaller.appspotmail.com Signed-off-by: Tomas Bortoli <tomasbort...@gmail.com> [ Added protection around freeing prog_stack[i].pred ] Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org> --- kernel/trace/trace_events_filter.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) 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); } -- 2.20.1
