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commit 8ec321e96e056de84022c032ffea253431a83c3c upstream. The syzbot fuzzer found a slab-out-of-bounds bug in the HID report handler. The bug was caused by a report descriptor which included a field with size 12 bits and count 4899, for a total size of 7349 bytes. The usbhid driver uses at most a single-page 4-KB buffer for reports. In the test there wasn't any problem about overflowing the buffer, since only one byte was received from the device. Rather, the bug occurred when the HID core tried to extract the data from the report fields, which caused it to try reading data beyond the end of the allocated buffer. This patch fixes the problem by rejecting any report whose total length exceeds the HID_MAX_BUFFER_SIZE limit (minus one byte to allow for a possible report index). In theory a device could have a report longer than that, but if there was such a thing we wouldn't handle it correctly anyway. Reported-and-tested-by: syzbot+09ef48aa58261464b621@syzkaller.appspotmail.com Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: <stable@vger.kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.