On Tue, Apr 06, 2021 at 04:39:21PM -0700, David Miller wrote: > From: Anirudh Rayabharam <mail@xxxxxxxxxxxxx> > Date: Tue, 6 Apr 2021 18:13:59 +0530 > > > Multiple ttys try to claim the same the minor number causing a double > > unregistration of the same device. The first unregistration succeeds > > but the next one results in a null-ptr-deref. > > > > The get_free_serial_index() function returns an available minor number > > but doesn't assign it immediately. The assignment is done by the caller > > later. But before this assignment, calls to get_free_serial_index() > > would return the same minor number. > > > > Fix this by modifying get_free_serial_index to assign the minor number > > immediately after one is found to be and rename it to obtain_minor() > > to better reflect what it does. Similary, rename set_serial_by_index() > > to release_minor() and modify it to free up the minor number of the > > given hso_serial. Every obtain_minor() should have corresponding > > release_minor() call. > > > > Reported-by: syzbot+c49fe6089f295a05e6f8@xxxxxxxxxxxxxxxxxxxxxxxxx > > Tested-by: syzbot+c49fe6089f295a05e6f8@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > Signed-off-by: Anirudh Rayabharam <mail@xxxxxxxxxxxxx> > > This adds a new build warning: > > CC [M] drivers/net/usb/hso.o > drivers/net/usb/hso.c: In function ‘hso_serial_common_create’: > drivers/net/usb/hso.c:2256:6: warning: unused variable ‘minor’ [-Wunused-variable] > > Please fix this and add an appropriate Fixes: tag, thank you. I have sent out a v2 with these changes. Thanks! - Anirudh.
