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https://github.com/Divested-Mobile/DivestOS-Build.git
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72 lines
3.5 KiB
Diff
72 lines
3.5 KiB
Diff
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From add333a81a16abbd4f106266a2553677a165725f Mon Sep 17 00:00:00 2001
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From: Alan Stern <stern@rowland.harvard.edu>
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Date: Fri, 9 Dec 2016 15:18:43 -0500
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Subject: [PATCH] USB: gadgetfs: fix use-after-free bug
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Andrey Konovalov reports that fuzz testing with syzkaller causes a
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KASAN use-after-free bug report in gadgetfs:
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BUG: KASAN: use-after-free in gadgetfs_setup+0x208a/0x20e0 at addr ffff88003dfe5bf2
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Read of size 2 by task syz-executor0/22994
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CPU: 3 PID: 22994 Comm: syz-executor0 Not tainted 4.9.0-rc7+ #16
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Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
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ffff88006df06a18 ffffffff81f96aba ffffffffe0528500 1ffff1000dbe0cd6
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ffffed000dbe0cce ffff88006df068f0 0000000041b58ab3 ffffffff8598b4c8
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ffffffff81f96828 1ffff1000dbe0ccd ffff88006df06708 ffff88006df06748
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Call Trace:
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<IRQ> [ 201.343209] [< inline >] __dump_stack lib/dump_stack.c:15
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<IRQ> [ 201.343209] [<ffffffff81f96aba>] dump_stack+0x292/0x398 lib/dump_stack.c:51
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[<ffffffff817e4dec>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:159
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[< inline >] print_address_description mm/kasan/report.c:197
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[<ffffffff817e5080>] kasan_report_error+0x1f0/0x4e0 mm/kasan/report.c:286
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[< inline >] kasan_report mm/kasan/report.c:306
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[<ffffffff817e562a>] __asan_report_load_n_noabort+0x3a/0x40 mm/kasan/report.c:337
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[< inline >] config_buf drivers/usb/gadget/legacy/inode.c:1298
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[<ffffffff8322c8fa>] gadgetfs_setup+0x208a/0x20e0 drivers/usb/gadget/legacy/inode.c:1368
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[<ffffffff830fdcd0>] dummy_timer+0x11f0/0x36d0 drivers/usb/gadget/udc/dummy_hcd.c:1858
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[<ffffffff814807c1>] call_timer_fn+0x241/0x800 kernel/time/timer.c:1308
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[< inline >] expire_timers kernel/time/timer.c:1348
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[<ffffffff81482de6>] __run_timers+0xa06/0xec0 kernel/time/timer.c:1641
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[<ffffffff814832c1>] run_timer_softirq+0x21/0x80 kernel/time/timer.c:1654
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[<ffffffff84f4af8b>] __do_softirq+0x2fb/0xb63 kernel/softirq.c:284
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The cause of the bug is subtle. The dev_config() routine gets called
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twice by the fuzzer. The first time, the user data contains both a
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full-speed configuration descriptor and a high-speed config
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descriptor, causing dev->hs_config to be set. But it also contains an
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invalid device descriptor, so the buffer containing the descriptors is
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deallocated and dev_config() returns an error.
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The second time dev_config() is called, the user data contains only a
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full-speed config descriptor. But dev->hs_config still has the stale
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pointer remaining from the first call, causing the routine to think
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that there is a valid high-speed config. Later on, when the driver
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dereferences the stale pointer to copy that descriptor, we get a
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use-after-free access.
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The fix is simple: Clear dev->hs_config if the passed-in data does not
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contain a high-speed config descriptor.
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Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
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Reported-by: Andrey Konovalov <andreyknvl@google.com>
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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 | 2 ++
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1 file changed, 2 insertions(+)
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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 01ed3bc0c3c8e..f1ca339426073 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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@@ -1800,6 +1800,8 @@ dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
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goto fail;
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kbuf += total;
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length -= total;
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+ } else {
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+ dev->hs_config = NULL;
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}
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/* could support multiple configs, using another encoding! */
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