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authorLee Jones <lee@kernel.org>2023-04-20 08:27:18 +0100
committerJassi Brar <jaswinder.singh@linaro.org>2023-05-04 00:53:31 -0500
commit2d1e952a2b8e5e92d8d55ac88a7cf7ca5ea591ad (patch)
tree795e8344aa6eb9f378584d1abc545f482cb50b76 /drivers
parentbe884585852e7d8336e765504399972b3034a89f (diff)
mailbox: mailbox-test: Fix potential double-free in mbox_test_message_write()
If a user can make copy_from_user() fail, there is a potential for UAF/DF due to a lack of locking around the allocation, use and freeing of the data buffers. This issue is not theoretical. I managed to author a POC for it: BUG: KASAN: double-free in kfree+0x5c/0xac Free of addr ffff29280be5de00 by task poc/356 CPU: 1 PID: 356 Comm: poc Not tainted 6.1.0-00001-g961aa6552c04-dirty #20 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace.part.0+0xe0/0xf0 show_stack+0x18/0x40 dump_stack_lvl+0x64/0x80 print_report+0x188/0x48c kasan_report_invalid_free+0xa0/0xc0 ____kasan_slab_free+0x174/0x1b0 __kasan_slab_free+0x18/0x24 __kmem_cache_free+0x130/0x2e0 kfree+0x5c/0xac mbox_test_message_write+0x208/0x29c full_proxy_write+0x90/0xf0 vfs_write+0x154/0x440 ksys_write+0xcc/0x180 __arm64_sys_write+0x44/0x60 invoke_syscall+0x60/0x190 el0_svc_common.constprop.0+0x7c/0x160 do_el0_svc+0x40/0xf0 el0_svc+0x2c/0x6c el0t_64_sync_handler+0xf4/0x120 el0t_64_sync+0x18c/0x190 Allocated by task 356: kasan_save_stack+0x3c/0x70 kasan_set_track+0x2c/0x40 kasan_save_alloc_info+0x24/0x34 __kasan_kmalloc+0xb8/0xc0 kmalloc_trace+0x58/0x70 mbox_test_message_write+0x6c/0x29c full_proxy_write+0x90/0xf0 vfs_write+0x154/0x440 ksys_write+0xcc/0x180 __arm64_sys_write+0x44/0x60 invoke_syscall+0x60/0x190 el0_svc_common.constprop.0+0x7c/0x160 do_el0_svc+0x40/0xf0 el0_svc+0x2c/0x6c el0t_64_sync_handler+0xf4/0x120 el0t_64_sync+0x18c/0x190 Freed by task 357: kasan_save_stack+0x3c/0x70 kasan_set_track+0x2c/0x40 kasan_save_free_info+0x38/0x5c ____kasan_slab_free+0x13c/0x1b0 __kasan_slab_free+0x18/0x24 __kmem_cache_free+0x130/0x2e0 kfree+0x5c/0xac mbox_test_message_write+0x208/0x29c full_proxy_write+0x90/0xf0 vfs_write+0x154/0x440 ksys_write+0xcc/0x180 __arm64_sys_write+0x44/0x60 invoke_syscall+0x60/0x190 el0_svc_common.constprop.0+0x7c/0x160 do_el0_svc+0x40/0xf0 el0_svc+0x2c/0x6c el0t_64_sync_handler+0xf4/0x120 el0t_64_sync+0x18c/0x190 Signed-off-by: Lee Jones <lee@kernel.org> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/mailbox/mailbox-test.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c
index 51e62817f243..c4a705c30331 100644
--- a/drivers/mailbox/mailbox-test.c
+++ b/drivers/mailbox/mailbox-test.c
@@ -12,6 +12,7 @@
#include <linux/kernel.h>
#include <linux/mailbox_client.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
@@ -39,6 +40,7 @@ struct mbox_test_device {
char *signal;
char *message;
spinlock_t lock;
+ struct mutex mutex;
wait_queue_head_t waitq;
struct fasync_struct *async_queue;
struct dentry *root_debugfs_dir;
@@ -111,6 +113,8 @@ static ssize_t mbox_test_message_write(struct file *filp,
return -EINVAL;
}
+ mutex_lock(&tdev->mutex);
+
tdev->message = kzalloc(MBOX_MAX_MSG_LEN, GFP_KERNEL);
if (!tdev->message)
return -ENOMEM;
@@ -145,6 +149,8 @@ out:
kfree(tdev->message);
tdev->signal = NULL;
+ mutex_unlock(&tdev->mutex);
+
return ret < 0 ? ret : count;
}
@@ -393,6 +399,7 @@ static int mbox_test_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, tdev);
spin_lock_init(&tdev->lock);
+ mutex_init(&tdev->mutex);
if (tdev->rx_channel) {
tdev->rx_buffer = devm_kzalloc(&pdev->dev,