79 lines
3.2 KiB
Diff
79 lines
3.2 KiB
Diff
From: Kyungtae Kim <kt0755@gmail.com>
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Date: Sun, 10 May 2020 05:43:34 +0000
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Subject: USB: gadget: fix illegal array access in binding with UDC
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Origin: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit?id=a105bb549252e3e8bd9db0bdd81cdd6a853e4238
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2020-13143
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commit 15753588bcd4bbffae1cca33c8ced5722477fe1f upstream.
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FuzzUSB (a variant of syzkaller) found an illegal array access
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using an incorrect index while binding a gadget with UDC.
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Reference: https://www.spinics.net/lists/linux-usb/msg194331.html
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This bug occurs when a size variable used for a buffer
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is misused to access its strcpy-ed buffer.
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Given a buffer along with its size variable (taken from user input),
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from which, a new buffer is created using kstrdup().
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Due to the original buffer containing 0 value in the middle,
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the size of the kstrdup-ed buffer becomes smaller than that of the original.
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So accessing the kstrdup-ed buffer with the same size variable
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triggers memory access violation.
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The fix makes sure no zero value in the buffer,
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by comparing the strlen() of the orignal buffer with the size variable,
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so that the access to the kstrdup-ed buffer is safe.
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BUG: KASAN: slab-out-of-bounds in gadget_dev_desc_UDC_store+0x1ba/0x200
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drivers/usb/gadget/configfs.c:266
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Read of size 1 at addr ffff88806a55dd7e by task syz-executor.0/17208
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CPU: 2 PID: 17208 Comm: syz-executor.0 Not tainted 5.6.8 #1
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Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
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Call Trace:
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__dump_stack lib/dump_stack.c:77 [inline]
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dump_stack+0xce/0x128 lib/dump_stack.c:118
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print_address_description.constprop.4+0x21/0x3c0 mm/kasan/report.c:374
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__kasan_report+0x131/0x1b0 mm/kasan/report.c:506
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kasan_report+0x12/0x20 mm/kasan/common.c:641
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__asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:132
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gadget_dev_desc_UDC_store+0x1ba/0x200 drivers/usb/gadget/configfs.c:266
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flush_write_buffer fs/configfs/file.c:251 [inline]
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configfs_write_file+0x2f1/0x4c0 fs/configfs/file.c:283
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__vfs_write+0x85/0x110 fs/read_write.c:494
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vfs_write+0x1cd/0x510 fs/read_write.c:558
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ksys_write+0x18a/0x220 fs/read_write.c:611
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__do_sys_write fs/read_write.c:623 [inline]
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__se_sys_write fs/read_write.c:620 [inline]
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__x64_sys_write+0x73/0xb0 fs/read_write.c:620
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do_syscall_64+0x9e/0x510 arch/x86/entry/common.c:294
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entry_SYSCALL_64_after_hwframe+0x49/0xbe
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Signed-off-by: Kyungtae Kim <kt0755@gmail.com>
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Reported-and-tested-by: Kyungtae Kim <kt0755@gmail.com>
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Cc: Felipe Balbi <balbi@kernel.org>
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Cc: stable <stable@vger.kernel.org>
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Link: https://lore.kernel.org/r/20200510054326.GA19198@pizza01
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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drivers/usb/gadget/configfs.c | 3 +++
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1 file changed, 3 insertions(+)
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diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
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index ab9ac48a751a..a7709d126b29 100644
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--- a/drivers/usb/gadget/configfs.c
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+++ b/drivers/usb/gadget/configfs.c
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@@ -260,6 +260,9 @@ static ssize_t gadget_dev_desc_UDC_store(struct config_item *item,
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char *name;
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int ret;
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+ if (strlen(page) < len)
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+ return -EOVERFLOW;
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+
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name = kstrdup(page, GFP_KERNEL);
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if (!name)
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return -ENOMEM;
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--
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2.27.0.rc0
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