Description
In the Linux kernel, the following vulnerability has been resolved: xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata() The TX metadata area resides in the UMEM buffer which is memory-mapped and concurrently writable by userspace. In xsk_skb_metadata(), csum_start and csum_offset are read from shared memory for bounds validation, then read again for skb assignment. A malicious userspace application can race to overwrite these values between the two reads, bypassing the bounds check and causing out-of-bounds memory access during checksum computation in the transmit path. Fix this by reading csum_start and csum_offset into local variables once, then using the local copies for both validation and assignment. Note that other metadata fields (flags, launch_time) and the cached csum fields may be mutually inconsistent due to concurrent userspace writes, but this is benign: the only security-critical invariant is that each field's validated value is the same one used, which local caching guarantees.
CVSS breakdown
Affected products
- Linux / Linux48eb03dd26304c24f03bdbb9382e89c8564e71df – 0dfe05b938435892875e07771170051346412df9
- Linux / Linux48eb03dd26304c24f03bdbb9382e89c8564e71df – bfdfd2706d5fb2cd496a1506e680daf979309c8b
- Linux / Linux48eb03dd26304c24f03bdbb9382e89c8564e71df – 22ba97ea9cc1f63a0d0244fae38057ed452b6ac7
- Linux / Linux6.8 – 6.8
- Linux / Linux0 – 6.8
- Linux / Linux6.18.36 – 6.18.*
- Linux / Linux7.0.13 – 7.0.*
- Linux / Linux7.1 – *