n0k0 has uploaded a new patch set (#3). ( https://gerrit.osmocom.org/c/osmo-ggsn/+/42885?usp=email )
Change subject: gtp: fix OOB write in PDP ctx GSN-Address decode ...................................................................... gtp: fix OOB write in PDP ctx GSN-Address decode gtp_decode_pdp_ctx() takes the GSN-Address sub-field lengths of a PDP Context IE (gsnrc / gsnru, the GGSN control- and user-plane addresses) straight from the wire and memcpy()s that many bytes into the fixed 16-byte 'struct ul16_t' v[] array, with no check against the destination size. decode_pdp_ctx_len_check() only validates the declared lengths against the *input* buffer, never against the destination capacity, so a wire length of 17..255 overflows the 16-byte field by up to 239 bytes, clobbering adjacent struct pdp_t state. The PDP Context IE is carried in SGSN Context Response / Forward Relocation messages exchanged between peer GSNs over Gn/Gp, so a malicious or spoofed peer GSN can trigger this. The same libgtp decoder is linked by osmo-sgsn, so it is affected as well. A GSN address is 4 (IPv4) or 16 (IPv6) bytes, so reject any length that does not fit the destination before copying. This issue has been assigned the CVE candidate identifier CAN-2026-2051035. Change-Id: Id69e82fe1a16933d8c6b9c848a2ede29f7920d98 --- M gtp/gtp.c 1 file changed, 12 insertions(+), 0 deletions(-) git pull ssh://gerrit.osmocom.org:29418/osmo-ggsn refs/changes/85/42885/3 -- To view, visit https://gerrit.osmocom.org/c/osmo-ggsn/+/42885?usp=email To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings?usp=email Gerrit-MessageType: newpatchset Gerrit-Project: osmo-ggsn Gerrit-Branch: master Gerrit-Change-Id: Id69e82fe1a16933d8c6b9c848a2ede29f7920d98 Gerrit-Change-Number: 42885 Gerrit-PatchSet: 3 Gerrit-Owner: n0k0 <[email protected]>
