Messages in this thread | | | Date | Tue, 06 Apr 2021 16:39:21 -0700 (PDT) | Subject | Re: [PATCH] net: hso: fix null-ptr-deref during tty device unregistration | From | David Miller <> |
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From: Anirudh Rayabharam <mail@anirudhrb.com> 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@syzkaller.appspotmail.com > Tested-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com > > Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
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.
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