Pete Zaitcev 19e6317d24 usb: mon: Fix a deadlock in usbmon between mmap and read ... The problem arises because our read() function grabs a lock of the circular buffer, finds something of interest, then invokes copy_to_user() straight from the buffer, which in turn takes mm->mmap_sem. In the same time, the callback mon_bin_vma_fault() is invoked under mm->mmap_sem. It attempts to take the fetch lock and deadlocks. This patch does away with protecting of our page list with any semaphores, and instead relies on the kernel not close the device while mmap is active in a process. In addition, we prohibit re-sizing of a buffer while mmap is active. This way, when (now unlocked) fault is processed, it works with the page that is intended to be mapped-in, and not some other random page. Note that this may have an ABI impact, but hopefully no legitimate program is this wrong. Signed-off-by: Pete Zaitcev <zaitcev@redhat.com> Reported-by: syzbot+56f9673bb4cdcbeb0e92@syzkaller.appspotmail.com Reviewed-by: Alan Stern <stern@rowland.harvard.edu> Fixes: 46eb14a6e1 ("USB: fix usbmon BUG trigger") Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20191204203941.3503452b@suzdal.zaitcev.lan Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2019-12-10 11:41:20 +01:00
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Kconfig	docs: usb: rename files to .rst and add them to drivers-api	2019-06-20 14:28:36 +02:00
Makefile	USB: add SPDX identifiers to all remaining Makefiles	2017-11-07 15:53:48 +01:00
mon_bin.c	usb: mon: Fix a deadlock in usbmon between mmap and read	2019-12-10 11:41:20 +01:00
mon_main.c	USB: add SPDX identifiers to all remaining files in drivers/usb/	2017-11-04 11:48:02 +01:00
mon_stat.c
mon_text.c	USB: mon: no need to check return value of debugfs_create functions	2018-05-31 12:54:21 +02:00
usb_mon.h