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authorHe, Bo <bo.he@intel.com>2019-03-14 05:28:21 +0300
committerJiri Kosina <jkosina@suse.cz>2019-03-19 17:41:08 +0300
commitcef0d4948cb0a02db37ebfdc320e127c77ab1637 (patch)
treea6dd022b559573e75c2df7ef780fd4ddc0b77c55 /drivers/hid
parent6c44b15e1c9076d925d5236ddadf1318b0a25ce2 (diff)
downloadlinux-cef0d4948cb0a02db37ebfdc320e127c77ab1637.tar.xz
HID: debug: fix race condition with between rdesc_show() and device removal
There is a race condition that could happen if hid_debug_rdesc_show() is running while hdev is in the process of going away (device removal, system suspend, etc) which could result in NULL pointer dereference: BUG: unable to handle kernel paging request at 0000000783316040 CPU: 1 PID: 1512 Comm: getevent Tainted: G U O 4.19.20-quilt-2e5dc0ac-00029-gc455a447dd55 #1 RIP: 0010:hid_dump_device+0x9b/0x160 Call Trace: hid_debug_rdesc_show+0x72/0x1d0 seq_read+0xe0/0x410 full_proxy_read+0x5f/0x90 __vfs_read+0x3a/0x170 vfs_read+0xa0/0x150 ksys_read+0x58/0xc0 __x64_sys_read+0x1a/0x20 do_syscall_64+0x55/0x110 entry_SYSCALL_64_after_hwframe+0x49/0xbe Grab driver_input_lock to make sure the input device exists throughout the whole process of dumping the rdesc. [jkosina@suse.cz: update changelog a bit] Signed-off-by: he, bo <bo.he@intel.com> Signed-off-by: "Zhang, Jun" <jun.zhang@intel.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid')
-rw-r--r--drivers/hid/hid-debug.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index ac9fda1b5a72..1384e57182af 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -1060,10 +1060,15 @@ static int hid_debug_rdesc_show(struct seq_file *f, void *p)
seq_printf(f, "\n\n");
/* dump parsed data and input mappings */
+ if (down_interruptible(&hdev->driver_input_lock))
+ return 0;
+
hid_dump_device(hdev, f);
seq_printf(f, "\n");
hid_dump_input_mapping(hdev, f);
+ up(&hdev->driver_input_lock);
+
return 0;
}