bpf: Check params size before reading reserved fields

Overview

In the Linux kernel, the following vulnerability has been resolved:

bpf: Check params size before reading reserved fields

bpf_crypto_ctx_create() is a kfunc whose second argument is declared with the __sz annotation, so the verifier only guarantees that params__sz bytes of params are valid. The function nevertheless reads params->reserved[0] and params->reserved[1] (offsets 14 and 15) before comparing params__sz against the size of struct bpf_crypto_params, so a BPF program can pass a shorter buffer and have the kernel read past the region that was validated for it.

Move the size check in front of the reserved field reads.

Affected

• Linux >= 3e1c6f35409f9e447bf37f64840f5b65576bfb78 < e03253f5d65ebcd2a6d479f140c3bd9c7e4fb84a
• Linux >= 3e1c6f35409f9e447bf37f64840f5b65576bfb78 < cd12d3e08620257fbcaa262785d7f4b9473afc7a
• Linux >= 3e1c6f35409f9e447bf37f64840f5b65576bfb78 < 86a0e945fb645ea90233fde239cd2de79f01974c
• Linux >= 3e1c6f35409f9e447bf37f64840f5b65576bfb78 < a11212910cf09b2fe8db9afa41ef60c4f81879c5
• Linux 6.10

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.