Messages in this thread | | | Date | Fri, 8 Jan 2021 14:52:09 +0100 (CET) | From | Jiri Kosina <> | Subject | Re: [PATCH] HID: core: detect and skip invalid inputs to snto32() |
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On Wed, 16 Dec 2020, Randy Dunlap wrote:
> Prevent invalid (0, 0) inputs to hid-core's snto32() function. > > Maybe it is just the dummy device here that is causing this, but > there are hundreds of calls to snto32(0, 0). Having n (bits count) > of 0 is causing the current UBSAN trap with a shift value of > 0xffffffff (-1, or n - 1 in this function). > > Either of the value to shift being 0 or the bits count being 0 can be > handled by just returning 0 to the caller, avoiding the following > complex shift + OR operations: > > return value & (1 << (n - 1)) ? value | (~0U << n) : value; > > Fixes: dde5845a529f ("[PATCH] Generic HID layer - code split") > Signed-off-by: Randy Dunlap <rdunlap@infradead.org> > Reported-by: syzbot+1e911ad71dd4ea72e04a@syzkaller.appspotmail.com > Cc: Jiri Kosina <jikos@kernel.org> > Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com> > Cc: linux-input@vger.kernel.org > --- > drivers/hid/hid-core.c | 3 +++ > 1 file changed, 3 insertions(+) > > --- lnx-510.orig/drivers/hid/hid-core.c > +++ lnx-510/drivers/hid/hid-core.c > @@ -1307,6 +1307,9 @@ EXPORT_SYMBOL_GPL(hid_open_report); > > static s32 snto32(__u32 value, unsigned n) > { > + if (!value || !n) > + return 0; > +
Given the fact that this has been in the code basically since ever, we're probably fine, but it's good to have this fixed nevertheless. Applied conservatively to hid.git#for-5.12/core.
Thanks,
-- Jiri Kosina SUSE Labs
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