On 03/09/2018 05:27 AM, Florian Westphal wrote:
ebt_among is special, it has a dynamic match size and is exempt
from the central size checks.
commit c4585a2823edf ("bridge: ebt_among: add missing match size checks")
added validation for pool size, but missed fact that the macros
ebt_among_wh_src/dst can already return out-of-bound result because
they do not check value of wh_src/dst_ofs (an offset) vs. the size
of the match that userspace gave to us.
v2:
check that offset has correct alignment.
Paolo Abeni points out that we should also check that src/dst
wormhash arrays do not overlap, and src + length lines up with
start of dst (or vice versa).
v3: compact wormhash_sizes_valid() part
NB: Fixes tag is intentionally wrong, this bug exists from day
one when match was added for 2.6 kernel. Tag is there so stable
maintainers will notice this one too.
Tested with same rules from the earlier patch.
Fixes: c4585a2823edf ("bridge: ebt_among: add missing match size checks")
Reported-by: <syzbot+bdabab6f1983a03fc009@xxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
v5: this is really v3 again, but with explicit (int)sizeof()
cast rather than use of temporary 'int minsize'.
objdump shows identical output for v3/v4/v5.
SGTM, thanks Florian ;)
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
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