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| author | cinap_lenrek <cinap_lenrek@felloff.net> | 2020-04-27 19:55:42 +0200 |
|---|---|---|
| committer | cinap_lenrek <cinap_lenrek@felloff.net> | 2020-04-27 19:55:42 +0200 |
| commit | 39c3fd117ab4988c041800490b23c2aedb1858d3 (patch) | |
| tree | 22125537078ad9230be88315ce717023ea0f6645 /sys/src/cmd/cpp | |
| parent | 00bfe3ec2bb2f0e5e33130cb32655453e37abba6 (diff) | |
lib9p: reject reads on closed fids and writes on directories
mischief provided the following test that shows the issue:
ramfs -S crash
aux/9pcon /srv/crash <<EOF
Tversion 8192 9P2000
Tattach 0 -1 $user ''
Tcreate 0 dir 020000000777 0
Tattach 5 -1 $user ''
Twalk 5 6 dir
Tread 6 0 512
EOF
the problem is that lib9p wrongly allowed reads on closed fids,
due to the permission check only considering the lower 2 bits.
a closed fid has fid->omode == -1 and it would pass on read for:
(-1 & 3) == 3 == OEXEC
the following change explicitely checks for for the closed case
and also rejects writes on directories (they are rejected on
open/create, but a broken 9p client could still issue the request).
Diffstat (limited to 'sys/src/cmd/cpp')
0 files changed, 0 insertions, 0 deletions