misc: sgi-gru: fix use-after-free error in gru_set_context_option, gru_fault and...

[ Upstream commit 643a16a0eb1d6ac23744bb6e90a00fc21148a9dc ]

In some bad situation, the gts may be freed gru_check_chiplet_assignment.
The call chain can be gru_unload_context->gru_free_gru_context->gts_drop
and kfree finally. However, the caller didn't know if the gts is freed
or not and use it afterwards. This will trigger a Use after Free bug.

Fix it by introducing a return value to see if it's in error path or not.
Free the gts in caller if gru_check_chiplet_assignment check failed.

Fixes: 55484c45dbec ("gru: allow users to specify gru chiplet 2")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Acked-by: Dimitri Sivanich <sivanich@hpe.com>
Link: https://lore.kernel.org/r/20221110035033.19498-1-zyytlz.wz@163.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
index d7ef61e..b836936 100644 (file)
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -648,6 +648,7 @@ int gru_handle_user_call_os(unsigned long cb)
        if ((cb & (GRU_HANDLE_STRIDE - 1)) || ucbnum >= GRU_NUM_CB)
                return -EINVAL;
 
+again:
        gts = gru_find_lock_gts(cb);
        if (!gts)
                return -EINVAL;
@@ -656,7 +657,11 @@ int gru_handle_user_call_os(unsigned long cb)
        if (ucbnum >= gts->ts_cbr_au_count * GRU_CBR_AU_SIZE)
                goto exit;
 
-       gru_check_context_placement(gts);
+       if (gru_check_context_placement(gts)) {
+               gru_unlock_gts(gts);
+               gru_unload_context(gts, 1);
+               goto again;
+       }
 
        /*
         * CCH may contain stale data if ts_force_cch_reload is set.
@@ -874,7 +879,11 @@ int gru_set_context_option(unsigned long arg)
                } else {
                        gts->ts_user_blade_id = req.val1;
                        gts->ts_user_chiplet_id = req.val0;
-                       gru_check_context_placement(gts);
+                       if (gru_check_context_placement(gts)) {
+                               gru_unlock_gts(gts);
+                               gru_unload_context(gts, 1);
+                               return ret;
+                       }
                }
                break;
        case sco_gseg_owner:

diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c
index 9afda47..3a16eb8 100644 (file)
--- a/drivers/misc/sgi-gru/grumain.c
+++ b/drivers/misc/sgi-gru/grumain.c
@@ -716,9 +716,10 @@ static int gru_check_chiplet_assignment(struct gru_state *gru,
  * chiplet. Misassignment can occur if the process migrates to a different
  * blade or if the user changes the selected blade/chiplet.
  */
-void gru_check_context_placement(struct gru_thread_state *gts)
+int gru_check_context_placement(struct gru_thread_state *gts)
 {
        struct gru_state *gru;
+       int ret = 0;
 
        /*
         * If the current task is the context owner, verify that the
@@ -726,15 +727,23 @@ void gru_check_context_placement(struct gru_thread_state *gts)
         * references. Pthread apps use non-owner references to the CBRs.
         */
        gru = gts->ts_gru;
+       /*
+        * If gru or gts->ts_tgid_owner isn't initialized properly, return
+        * success to indicate that the caller does not need to unload the
+        * gru context.The caller is responsible for their inspection and
+        * reinitialization if needed.
+        */
        if (!gru || gts->ts_tgid_owner != current->tgid)
-               return;
+               return ret;
 
        if (!gru_check_chiplet_assignment(gru, gts)) {
                STAT(check_context_unload);
-               gru_unload_context(gts, 1);
+               ret = -EINVAL;
        } else if (gru_retarget_intr(gts)) {
                STAT(check_context_retarget_intr);
        }
+
+       return ret;
 }
 
 
@@ -934,7 +943,12 @@ again:
        mutex_lock(&gts->ts_ctxlock);
        preempt_disable();
 
-       gru_check_context_placement(gts);
+       if (gru_check_context_placement(gts)) {
+               preempt_enable();
+               mutex_unlock(&gts->ts_ctxlock);
+               gru_unload_context(gts, 1);
+               return VM_FAULT_NOPAGE;
+       }
 
        if (!gts->ts_gru) {
                STAT(load_user_context);

diff --git a/drivers/misc/sgi-gru/grutables.h b/drivers/misc/sgi-gru/grutables.h
index e4c067c..5c97831 100644 (file)
--- a/drivers/misc/sgi-gru/grutables.h
+++ b/drivers/misc/sgi-gru/grutables.h
@@ -638,7 +638,7 @@ extern int gru_user_flush_tlb(unsigned long arg);
 extern int gru_user_unload_context(unsigned long arg);
 extern int gru_get_exception_detail(unsigned long arg);
 extern int gru_set_context_option(unsigned long address);
-extern void gru_check_context_placement(struct gru_thread_state *gts);
+extern int gru_check_context_placement(struct gru_thread_state *gts);
 extern int gru_cpu_fault_map_id(void);
 extern struct vm_area_struct *gru_find_vma(unsigned long vaddr);
 extern void gru_flush_all_tlb(struct gru_state *gru);