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Subject[PATCH v3] vt: Fix a missing-check bug in drivers/tty/vt/vt.c
In function con_init(), the pointer variable vc_cons[currcons].d, vc and
vc->vc_screenbuf is allocated a memory space via kzalloc(). And they are
used in the following codes.
However, when there is a memory allocation error, kzalloc() can fail.
Thus null pointer (vc_cons[currcons].d, vc and vc->vc_screenbuf)
dereference may happen. And it will cause the kernel to crash. Therefore,
we should check return value and handle the error.
Further, since the allcoation is in a loop, we should free all the
allocated memory in a loop.

Signed-off-by: Gen Zhang <blackgod016574@gmail.com>

---
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index fdd12f8..d50f68f 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -3350,10 +3350,14 @@ static int __init con_init(void)

for (currcons = 0; currcons < MIN_NR_CONSOLES; currcons++) {
vc_cons[currcons].d = vc = kzalloc(sizeof(struct vc_data), GFP_NOWAIT);
+ if (!vc)
+ goto fail1;
INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK);
tty_port_init(&vc->port);
visual_init(vc, currcons, 1);
vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_NOWAIT);
+ if (!vc->vc_screenbuf)
+ goto fail2;
vc_init(vc, vc->vc_rows, vc->vc_cols,
currcons || !vc->vc_sw->con_save_screen);
}
@@ -3375,6 +3379,16 @@ static int __init con_init(void)
register_console(&vt_console_driver);
#endif
return 0;
+fail1:
+ while (currcons > 0) {
+ currcons--;
+ kfree(vc_cons[currcons].d->vc_screenbuf);
+fail2:
+ kfree(vc_cons[currcons].d);
+ vc_cons[currcons].d = NULL;
+ }
+ console_unlock();
+ return -ENOMEM;
}
console_initcall(con_init);

---
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