Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: lwt_bpf: Restore reserved headroom after xmit program ip_finish_output2() expands an skb to LL_RESERVED_SPACE(dev) before LWT xmit. An LWT_XMIT BPF program can then modify the skb head and still return BPF_OK, so bpf_xmit() rechecks the remaining headroom before the skb continues to neighbour output. That recheck uses dst->dev->hard_header_len. This is not enough for the neighbour cached-header path: neigh_hh_output() copies the cached hardware header using the aligned hh_cache size, HH_DATA_MOD for short headers or HH_DATA_ALIGN(hh_len) otherwise. On Ethernet, hard_header_len is 14 but the cached copy needs 16 bytes. If an LWT_XMIT BPF program calls bpf_skb_change_head(skb, 1, 0), the skb can still have 15 bytes of headroom after the program. The existing check accepts that, after which neigh_hh_output() hits its headroom warning and drops the skb. Use LL_RESERVED_SPACE(dst->dev) in the post-BPF headroom check to match the reservation made before LWT xmit.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 before 753e5cdcca5474d230d62bb3489e5168ab27c272; affected 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 before c488071c3441fa34f5a87cd6c12ce2cc6304f20e; affected 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 before a38c0eb447e2dd0120a2ebcdba470f9505ac8907; affected 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 before de2b2004e16f2930eb689175e2c1998b0a68d499; affected 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 before 7d043e24520a273c362be5dd7d9c82796879a49b; affected 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 before 7cf561843ed0ad57501892a65abb77957e6c800f; affected 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 before 179a5b2171573d94a25c9aa8e1c9f9ac352ad316; affected 3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2 before 5fe7007aed9ad069b2bd77e5d0c875c64f5c0269 |
| Linux / Linux | affected 4.10; unaffected 0 before 4.10; unaffected 5.10.270 through 5.10.*; unaffected 5.15.221 through 5.15.*; unaffected 6.1.188 through 6.1.*; unaffected 6.6.157 through 6.6.*; unaffected 6.12.110 through 6.12.*; unaffected 6.18.52 through 6.18.*; unaffected 7.2.6 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/753e5cdcca5474d230d62bb3489e5168ab27c272
- https://git.kernel.org/stable/c/c488071c3441fa34f5a87cd6c12ce2cc6304f20e
- https://git.kernel.org/stable/c/a38c0eb447e2dd0120a2ebcdba470f9505ac8907
- https://git.kernel.org/stable/c/de2b2004e16f2930eb689175e2c1998b0a68d499
- https://git.kernel.org/stable/c/7d043e24520a273c362be5dd7d9c82796879a49b
- https://git.kernel.org/stable/c/7cf561843ed0ad57501892a65abb77957e6c800f
- https://git.kernel.org/stable/c/179a5b2171573d94a25c9aa8e1c9f9ac352ad316
- https://git.kernel.org/stable/c/5fe7007aed9ad069b2bd77e5d0c875c64f5c0269