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https://github.com/Divested-Mobile/DivestOS-Build.git
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90 lines
4.2 KiB
Diff
90 lines
4.2 KiB
Diff
From f50b878fed33e360d01dcdc31a8eeb1815d033d5 Mon Sep 17 00:00:00 2001
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From: Alan Stern <stern@rowland.harvard.edu>
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Date: Thu, 8 Jun 2017 13:55:59 -0400
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Subject: [PATCH] USB: gadget: fix GPF in gadgetfs
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A NULL-pointer dereference bug in gadgetfs was uncovered by syzkaller:
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> kasan: GPF could be caused by NULL-ptr deref or user memory access
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> general protection fault: 0000 [#1] SMP KASAN
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> Dumping ftrace buffer:
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> (ftrace buffer empty)
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> Modules linked in:
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> CPU: 2 PID: 4820 Comm: syz-executor0 Not tainted 4.12.0-rc4+ #5
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> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
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> task: ffff880039542dc0 task.stack: ffff88003bdd0000
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> RIP: 0010:__list_del_entry_valid+0x7e/0x170 lib/list_debug.c:51
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> RSP: 0018:ffff88003bdd6e50 EFLAGS: 00010246
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> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000010000
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> RDX: 0000000000000000 RSI: ffffffff86504948 RDI: ffffffff86504950
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> RBP: ffff88003bdd6e68 R08: ffff880039542dc0 R09: ffffffff8778ce00
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> R10: ffff88003bdd6e68 R11: dffffc0000000000 R12: 0000000000000000
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> R13: dffffc0000000000 R14: 1ffff100077badd2 R15: ffffffff864d2e40
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> FS: 0000000000000000(0000) GS:ffff88006dc00000(0000) knlGS:0000000000000000
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> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
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> CR2: 000000002014aff9 CR3: 0000000006022000 CR4: 00000000000006e0
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> Call Trace:
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> __list_del_entry include/linux/list.h:116 [inline]
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> list_del include/linux/list.h:124 [inline]
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> usb_gadget_unregister_driver+0x166/0x4c0 drivers/usb/gadget/udc/core.c:1387
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> dev_release+0x80/0x160 drivers/usb/gadget/legacy/inode.c:1187
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> __fput+0x332/0x7f0 fs/file_table.c:209
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> ____fput+0x15/0x20 fs/file_table.c:245
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> task_work_run+0x19b/0x270 kernel/task_work.c:116
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> exit_task_work include/linux/task_work.h:21 [inline]
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> do_exit+0x18a3/0x2820 kernel/exit.c:878
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> do_group_exit+0x149/0x420 kernel/exit.c:982
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> get_signal+0x77f/0x1780 kernel/signal.c:2318
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> do_signal+0xd2/0x2130 arch/x86/kernel/signal.c:808
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> exit_to_usermode_loop+0x1a7/0x240 arch/x86/entry/common.c:157
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> prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
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> syscall_return_slowpath+0x3ba/0x410 arch/x86/entry/common.c:263
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> entry_SYSCALL_64_fastpath+0xbc/0xbe
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> RIP: 0033:0x4461f9
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> RSP: 002b:00007fdac2b1ecf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
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> RAX: fffffffffffffe00 RBX: 00000000007080c8 RCX: 00000000004461f9
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> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000007080c8
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> RBP: 00000000007080a8 R08: 0000000000000000 R09: 0000000000000000
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> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
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> R13: 0000000000000000 R14: 00007fdac2b1f9c0 R15: 00007fdac2b1f700
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> Code: 00 00 00 00 ad de 49 39 c4 74 6a 48 b8 00 02 00 00 00 00 ad de
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> 48 89 da 48 39 c3 74 74 48 c1 ea 03 48 b8 00 00 00 00 00 fc ff df <80>
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> 3c 02 00 0f 85 92 00 00 00 48 8b 13 48 39 f2 75 66 49 8d 7c
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> RIP: __list_del_entry_valid+0x7e/0x170 lib/list_debug.c:51 RSP: ffff88003bdd6e50
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> ---[ end trace 30e94b1eec4831c8 ]---
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> Kernel panic - not syncing: Fatal exception
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The bug was caused by dev_release() failing to turn off its
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gadget_registered flag after unregistering the gadget driver. As a
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result, when a later user closed the device file before writing a
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valid set of descriptors, dev_release() thought the gadget had been
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registered and tried to unregister it, even though it had not been.
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This led to the NULL pointer dereference.
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The fix is simple: turn off the flag when the gadget is unregistered.
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Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
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Reported-and-tested-by: Andrey Konovalov <andreyknvl@google.com>
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CC: <stable@vger.kernel.org>
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Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
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---
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drivers/usb/gadget/legacy/inode.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
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index b9ca0a26cbd93..5ffd879f78868 100644
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--- a/drivers/usb/gadget/legacy/inode.c
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+++ b/drivers/usb/gadget/legacy/inode.c
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@@ -1183,8 +1183,10 @@ dev_release (struct inode *inode, struct file *fd)
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/* closing ep0 === shutdown all */
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- if (dev->gadget_registered)
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+ if (dev->gadget_registered) {
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usb_gadget_unregister_driver (&gadgetfs_driver);
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+ dev->gadget_registered = false;
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+ }
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/* at this point "good" hardware has disconnected the
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* device from USB; the host won't see it any more.
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