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05ab8f2647
The BPF_S_ANC_NLATTR and BPF_S_ANC_NLATTR_NEST extensions fail to check for a minimal message length before testing the supplied offset to be within the bounds of the message. This allows the subtraction of the nla header to underflow and therefore -- as the data type is unsigned -- allowing far to big offset and length values for the search of the netlink attribute. The remainder calculation for the BPF_S_ANC_NLATTR_NEST extension is also wrong. It has the minuend and subtrahend mixed up, therefore calculates a huge length value, allowing to overrun the end of the message while looking for the netlink attribute. The following three BPF snippets will trigger the bugs when attached to a UNIX datagram socket and parsing a message with length 1, 2 or 3. ,-[ PoC for missing size check in BPF_S_ANC_NLATTR ]-- | ld #0x87654321 | ldx #42 | ld #nla | ret a `--- ,-[ PoC for the same bug in BPF_S_ANC_NLATTR_NEST ]-- | ld #0x87654321 | ldx #42 | ld #nlan | ret a `--- ,-[ PoC for wrong remainder calculation in BPF_S_ANC_NLATTR_NEST ]-- | ; (needs a fake netlink header at offset 0) | ld #0 | ldx #42 | ld #nlan | ret a `--- Fix the first issue by ensuring the message length fulfills the minimal size constrains of a nla header. Fix the second bug by getting the math for the remainder calculation right. Fixes: |
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| .. | ||
| datagram.c | ||
| dev_addr_lists.c | ||
| dev_ioctl.c | ||
| dev.c | ||
| drop_monitor.c | ||
| dst.c | ||
| ethtool.c | ||
| fib_rules.c | ||
| filter.c | ||
| flow_dissector.c | ||
| flow.c | ||
| gen_estimator.c | ||
| gen_stats.c | ||
| iovec.c | ||
| link_watch.c | ||
| Makefile | ||
| neighbour.c | ||
| net_namespace.c | ||
| net-procfs.c | ||
| net-sysfs.c | ||
| net-sysfs.h | ||
| net-traces.c | ||
| netclassid_cgroup.c | ||
| netevent.c | ||
| netpoll.c | ||
| netprio_cgroup.c | ||
| pktgen.c | ||
| ptp_classifier.c | ||
| request_sock.c | ||
| rtnetlink.c | ||
| scm.c | ||
| secure_seq.c | ||
| skbuff.c | ||
| sock_diag.c | ||
| sock.c | ||
| stream.c | ||
| sysctl_net_core.c | ||
| timestamping.c | ||
| user_dma.c | ||
| utils.c | ||