Messages in this thread | | | Date | Mon, 26 Apr 2021 09:58:18 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH 4.4 22/32] net: hso: fix null-ptr-deref during tty device unregistration |
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On Mon, Apr 26, 2021 at 09:36:57AM +0200, Johan Hovold wrote: > On Mon, Apr 26, 2021 at 09:29:20AM +0200, Greg Kroah-Hartman wrote: > > From: Anirudh Rayabharam <mail@anirudhrb.com> > > > > commit 8a12f8836145ffe37e9c8733dce18c22fb668b66 upstream > > > > 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. > > > > Fixes: 72dc1c096c705 ("HSO: add option hso driver") > > Reported-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com > > Tested-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com > > Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com> > > Signed-off-by: David S. Miller <davem@davemloft.net> > > [sudip: adjust context] > > Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > --- > > drivers/net/usb/hso.c | 33 ++++++++++++--------------------- > > 1 file changed, 12 insertions(+), 21 deletions(-) > > We just got a regression report against this one. Perhaps better to hold > off until that has been resolved. > > https://lore.kernel.org/r/20210425233509.9ce29da49037e1a421000bdd@aruba.it
Good point, I'll go drop this from everywhere.
greg k-h
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