From 89fb6136ad7484e4e8f9b618e530e098cf573665 Mon Sep 17 00:00:00 2001 From: Alban Bedel Date: Thu, 23 Apr 2020 15:35:23 +1200 Subject: [PATCH] libubox: runqueue: fix use-after-free bug MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fixes a use-after-free bug in runqueue_task_kill(): Invalid read of size 8 at runqueue_task_kill (runqueue.c:200) by uloop_process_timeouts (uloop.c:505) by uloop_run_timeout (uloop.c:542) by uloop_run (uloop.h:111) by main (tests/test-runqueue.c:126) Address 0x5a4b058 is 24 bytes inside a block of size 208 free'd at free by runqueue_task_complete (runqueue.c:234) by runqueue_task_kill (runqueue.c:199) by uloop_process_timeouts (uloop.c:505) by uloop_run_timeout (uloop.c:542) by uloop_run (uloop.h:111) by main (tests/test-runqueue.c:126) Block was alloc'd at at calloc by add_sleeper (tests/test-runqueue.c:101) by main (tests/test-runqueue.c:123) Since commit 11e8afea (runqueue should call the complete handler from more places) the call to the complete() callback has been moved to runqueue_task_complete(). However in runqueue_task_kill() runqueue_task_complete() is called before the kill() callback. This will result in a use after free if the complete() callback frees the task struct. Furthermore runqueue_start_next() is already called at the end of runqueue_task_complete(), so there is no need to call it again in runqueue_task_kill(). The issue was that the _complete() callback frees the memory used by the task struct, which is then read after the _complete() callback returns. Ref: FS#3016 Signed-off-by: Alban Bedel [initial test case, kill cb comment fix] Signed-off-by: Chris Nisbet [testcase improvements and commit subject/description tweaks] Signed-off-by: Petr Štetiar --- runqueue.c | 3 +- runqueue.h | 2 +- tests/cram/test_runqueue.t | 46 ++++++++++++++++---------- tests/test-runqueue.c | 67 ++++++++++++++++++++++++++++++++------ 4 files changed, 87 insertions(+), 31 deletions(-) diff --git a/runqueue.c b/runqueue.c index a1d0133..d5719d1 100644 --- a/runqueue.c +++ b/runqueue.c @@ -196,11 +196,10 @@ void runqueue_task_kill(struct runqueue_task *t) if (!t->queued) return; - runqueue_task_complete(t); if (running && t->type->kill) t->type->kill(q, t); - runqueue_start_next(q); + runqueue_task_complete(t); } void runqueue_stop(struct runqueue *q) diff --git a/runqueue.h b/runqueue.h index 08879d4..9728c9c 100644 --- a/runqueue.h +++ b/runqueue.h @@ -63,7 +63,7 @@ struct runqueue_task_type { /* * called to kill a task. must not make any calls to runqueue_task_complete, - * it has already been removed from the list. + * which will be called after this returns. */ void (*kill)(struct runqueue *q, struct runqueue_task *t); }; diff --git a/tests/cram/test_runqueue.t b/tests/cram/test_runqueue.t index 227f414..cd9d96b 100644 --- a/tests/cram/test_runqueue.t +++ b/tests/cram/test_runqueue.t @@ -2,25 +2,35 @@ check that runqueue is producing expected results: $ [ -n "$TEST_BIN_DIR" ] && export PATH="$TEST_BIN_DIR:$PATH" $ valgrind --quiet --leak-check=full test-runqueue - [1/1] start 'sleep 1' - [1/1] cancel 'sleep 1' - [0/1] finish 'sleep 1' - [1/1] start 'sleep 1' - [1/1] cancel 'sleep 1' - [0/1] finish 'sleep 1' - [1/1] start 'sleep 1' - [1/1] cancel 'sleep 1' - [0/1] finish 'sleep 1' + [1/1] start 'sleep 1' (killer) + [1/1] killing process (killer) + [0/1] finish 'sleep 1' (killer) + [0/1] finish 'sleep 1' (killer) + [0/1] finish 'sleep 1' (killer) + [1/1] start 'sleep 1' (sleeper) + [1/1] cancel 'sleep 1' (sleeper) + [0/1] finish 'sleep 1' (sleeper) + [1/1] start 'sleep 1' (sleeper) + [1/1] cancel 'sleep 1' (sleeper) + [0/1] finish 'sleep 1' (sleeper) + [1/1] start 'sleep 1' (sleeper) + [1/1] cancel 'sleep 1' (sleeper) + [0/1] finish 'sleep 1' (sleeper) All done! $ test-runqueue-san - [1/1] start 'sleep 1' - [1/1] cancel 'sleep 1' - [0/1] finish 'sleep 1' - [1/1] start 'sleep 1' - [1/1] cancel 'sleep 1' - [0/1] finish 'sleep 1' - [1/1] start 'sleep 1' - [1/1] cancel 'sleep 1' - [0/1] finish 'sleep 1' + [1/1] start 'sleep 1' (killer) + [1/1] killing process (killer) + [0/1] finish 'sleep 1' (killer) + [0/1] finish 'sleep 1' (killer) + [0/1] finish 'sleep 1' (killer) + [1/1] start 'sleep 1' (sleeper) + [1/1] cancel 'sleep 1' (sleeper) + [0/1] finish 'sleep 1' (sleeper) + [1/1] start 'sleep 1' (sleeper) + [1/1] cancel 'sleep 1' (sleeper) + [0/1] finish 'sleep 1' (sleeper) + [1/1] start 'sleep 1' (sleeper) + [1/1] cancel 'sleep 1' (sleeper) + [0/1] finish 'sleep 1' (sleeper) All done! diff --git a/tests/test-runqueue.c b/tests/test-runqueue.c index 13ab864..fb99892 100644 --- a/tests/test-runqueue.c +++ b/tests/test-runqueue.c @@ -16,6 +16,7 @@ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ +#include #include #include #include @@ -26,8 +27,10 @@ static struct runqueue q; struct sleeper { - struct runqueue_process proc; int val; + bool kill; + struct uloop_timeout t; + struct runqueue_process proc; }; static void q_empty(struct runqueue *q) @@ -36,13 +39,19 @@ static void q_empty(struct runqueue *q) uloop_end(); } +static const char* sleeper_type(struct sleeper *s) +{ + return s->kill ? "killer" : "sleeper"; +} + static void q_sleep_run(struct runqueue *q, struct runqueue_task *t) { struct sleeper *s = container_of(t, struct sleeper, proc.task); char str[32]; pid_t pid; - fprintf(stderr, "[%d/%d] start 'sleep %d'\n", q->running_tasks, q->max_running_tasks, s->val); + fprintf(stderr, "[%d/%d] start 'sleep %d' (%s)\n", q->running_tasks, + q->max_running_tasks, s->val, sleeper_type(s)); pid = fork(); if (pid < 0) @@ -62,7 +71,8 @@ static void q_sleep_cancel(struct runqueue *q, struct runqueue_task *t, int type { struct sleeper *s = container_of(t, struct sleeper, proc.task); - fprintf(stderr, "[%d/%d] cancel 'sleep %d'\n", q->running_tasks, q->max_running_tasks, s->val); + fprintf(stderr, "[%d/%d] cancel 'sleep %d' (%s)\n", q->running_tasks, + q->max_running_tasks, s->val, sleeper_type(s)); runqueue_process_cancel_cb(q, t, type); } @@ -70,10 +80,40 @@ static void q_sleep_complete(struct runqueue *q, struct runqueue_task *p) { struct sleeper *s = container_of(p, struct sleeper, proc.task); - fprintf(stderr, "[%d/%d] finish 'sleep %d'\n", q->running_tasks, q->max_running_tasks, s->val); + fprintf(stderr, "[%d/%d] finish 'sleep %d' (%s) \n", q->running_tasks, + q->max_running_tasks, s->val, sleeper_type(s)); free(s); } +static void my_runqueue_process_kill_cb(struct runqueue *q, struct runqueue_task *p) +{ + struct sleeper *s = container_of(p, struct sleeper, proc.task); + + fprintf(stderr, "[%d/%d] killing process (%s)\n", q->running_tasks, + q->max_running_tasks, sleeper_type(s)); + runqueue_process_kill_cb(q, p); +} + +static void timer_cb(struct uloop_timeout *t) +{ + struct sleeper *s = container_of(t, struct sleeper, t); + if (s->kill) + runqueue_task_kill(&s->proc.task); +} + +static struct sleeper* create_sleeper(int val, const struct runqueue_task_type *type, bool kill) +{ + struct sleeper *s = calloc(1, sizeof(*s)); + s->kill = kill; + s->t.cb = timer_cb; + s->proc.task.type = type; + s->proc.task.run_timeout = 500; + s->proc.task.complete = q_sleep_complete; + s->val = val; + + return s; +} + static void add_sleeper(int val) { static const struct runqueue_task_type sleeper_type = { @@ -81,13 +121,19 @@ static void add_sleeper(int val) .cancel = q_sleep_cancel, .kill = runqueue_process_kill_cb, }; - struct sleeper *s; - s = calloc(1, sizeof(*s)); - s->proc.task.type = &sleeper_type; - s->proc.task.run_timeout = 500; - s->proc.task.complete = q_sleep_complete; - s->val = val; + static const struct runqueue_task_type killer_type = { + .run = q_sleep_run, + .cancel = q_sleep_cancel, + .kill = my_runqueue_process_kill_cb, + }; + + struct sleeper *k = create_sleeper(val, &killer_type, true); + uloop_timeout_set(&k->t, 100); + uloop_timeout_add(&k->t); + runqueue_task_add(&q, &k->proc.task, false); + + struct sleeper *s = create_sleeper(val, &sleeper_type, false); runqueue_task_add(&q, &s->proc.task, false); } @@ -105,6 +151,7 @@ int main(int argc, char **argv) add_sleeper(1); add_sleeper(1); add_sleeper(1); + uloop_run(); uloop_done();