Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: SUNRPC: Reject krb5 v2 wrap tokens with oversized ec field gss_krb5_unwrap_v2() sets buf->len to a logical length, which can be much smaller than head[0].iov_len (the allocated receive-page capacity). It then calls xdr_buf_trim() with a trim length derived from the 16-bit "extra count" (ec) field in the Kerberos v2 token header. The ec field is authenticated by the post-decrypt memcmp() against the encrypted header copy, so a randomly-mutated value is rejected. However, any peer holding a valid GSS context can legitimately encrypt a token whose ec exceeds the plaintext length. Per RFC 4121, such a token is structurally malformed. Although xdr_buf_trim() now clamps the buf->len subtraction to avoid unsigned underflow, the buffer is still left in a semantically invalid state (zero length, inconsistent iov lengths) when ec is oversized. Reject these tokens before calling xdr_buf_trim(), giving callers a well-defined GSS_S_DEFECTIVE_TOKEN error and keeping the xdr_buf internally consistent. The wrapped blob begins at a nonzero offset -- both callers pass len as offset + opaque_len -- so buf->len still counts the offset bytes that precede the blob. Compare the trim length against the remaining wrapped segment, buf->len - offset, rather than the whole buffer; comparing against buf->len alone leaves an offset-wide window in which an oversized ec passes the test and xdr_buf_trim() cuts into the bytes ahead of the blob.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected cf4c024b908353fcc48309374d39e3399d67dfd1 before ac9efc29346b6942e71f0e24a3178a9121330fab; affected cf4c024b908353fcc48309374d39e3399d67dfd1 before b5746095b59f4d11f39f08751d36bbdfd1e5deac; affected cf4c024b908353fcc48309374d39e3399d67dfd1 before 9fc6d6e6db49ab55208d5dd1c424c1d0d9aa7296; affected cf4c024b908353fcc48309374d39e3399d67dfd1 before 4abb44a29bb515df6f49123848765c70fc9b5021; affected cf4c024b908353fcc48309374d39e3399d67dfd1 before dfcd81ab45613d45996fbf483d4ef54b0ec90ab9; affected cf4c024b908353fcc48309374d39e3399d67dfd1 before 1f9856af065b6158271687e9788407b9573fd16f; affected cf4c024b908353fcc48309374d39e3399d67dfd1 before 880effc943ed82d6811f272ed3307c222b40f4d6; affected cf4c024b908353fcc48309374d39e3399d67dfd1 before ad484748eec0a66eac0f13ab53b3fbedb7333c91 |
| Linux / Linux | affected 3.13; unaffected 0 before 3.13; 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 6.12.109 through 6.12.*; unaffected 6.18.50 through 6.18.*; unaffected 7.2.4 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/ac9efc29346b6942e71f0e24a3178a9121330fab
- https://git.kernel.org/stable/c/b5746095b59f4d11f39f08751d36bbdfd1e5deac
- https://git.kernel.org/stable/c/9fc6d6e6db49ab55208d5dd1c424c1d0d9aa7296
- https://git.kernel.org/stable/c/4abb44a29bb515df6f49123848765c70fc9b5021
- https://git.kernel.org/stable/c/dfcd81ab45613d45996fbf483d4ef54b0ec90ab9
- https://git.kernel.org/stable/c/1f9856af065b6158271687e9788407b9573fd16f
- https://git.kernel.org/stable/c/880effc943ed82d6811f272ed3307c222b40f4d6
- https://git.kernel.org/stable/c/ad484748eec0a66eac0f13ab53b3fbedb7333c91
ADP enrichment
No English description supplied.
No references supplied.