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CVE-2026-93203

batman-adv: bla: avoid CRC corruption due to parallel claim add PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: batman-adv: bla: avoid CRC corruption due to parallel claim add batadv_bla_add_claim() is used to add claims and modify the backbone of claims for CLAIM frames from remote backbones and local packets. When it handles a claim, it needs to either * add the new claim's CRC to the backbone CRC * remove the already existing claim's CRC from the old backbone and add it to the new backbone But when the "new" claim code was running in parallel to the "change backbone" code, it can happen that the CRC was invalid because the backbone_gw of the claim was changed twice in the "new" claim code path: * CPU0 creates the claim for gateway A and publishes it in the claim hash. The crc16 of the address has not yet been added to A's crc at this point. * CPU1 processes a claim frame of gateway B for the same client, finds the just published claim, and performs the ownership change: it switches the pointer to B, removes the crc16 from A's crc - which never contained it - and adds it to B's crc. * CPU0 continues behind the creation branch, unconditionally switches the pointer back to A without compensating B's crc (its remove_crc is false for the creation path), and finally adds the crc16 to A's crc The CRC is then wrong for both: * claim belongs to A: but CRC is not part of backbone A's CRC * claim doesn't belong to B: CRC is still part of backbone B's CRC This wrong CRC is never recomputated from the stored claims. For local backbone claims, this can also not recovered using syncs. To avoid this, split the functionality in clear separate parts: * new claim which always adds claim CRC to the backbone CRC (but never changes the already set backbone_gw of the claim back) * update of existing claim which automatically changes the backbone_gw entry and only updates both backbone CRCs when there was an actual change

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 23721387c409087fd3b97e274f34d3ddc0970b74 before 3d4a9ae2c69c0fe4c3c69587288241243bb7a39b; affected 23721387c409087fd3b97e274f34d3ddc0970b74 before ad982d925f00d860d2467811256ffadcccd9e4a7; affected 23721387c409087fd3b97e274f34d3ddc0970b74 before d5b0e7574da5a485f4dbec32a15911900a4487c2; affected 23721387c409087fd3b97e274f34d3ddc0970b74 before a3e07db74f22a85aeeb51c600da5c98b9cbca11f; affected 23721387c409087fd3b97e274f34d3ddc0970b74 before 1d390db003cbb52cdd86837608bff3794501a5ea; affected 23721387c409087fd3b97e274f34d3ddc0970b74 before 8bcfa58c4277bff1882a23547c37ab08aa1de12f; affected 23721387c409087fd3b97e274f34d3ddc0970b74 before e54602d9e38db8573f2097d60c7ea8be0a5af1fa; affected 23721387c409087fd3b97e274f34d3ddc0970b74 before 08645ab95768b88e2ff85a89211994651710465b
Linux / Linuxaffected 3.5; unaffected 0 before 3.5; 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