diff options
| author | Chuck Lever | 2023-03-22 15:01:34 -0400 |
|---|---|---|
| committer | Chuck Lever | 2023-03-22 16:58:26 -0400 |
| commit | 5f24a8725fe7bc2c6adf7ce00dd3e818387d8995 (patch) | |
| tree | 51b1b8d3a00bbf156b8fe6752790b5fad14e19f6 /net/sunrpc | |
| parent | 27c934dd8832dd40fd34776f916dc201e18b319b (diff) | |
SUNRPC: Fix a crash in gss_krb5_checksum()
Anna says:
> KASAN reports [...] a slab-out-of-bounds in gss_krb5_checksum(),
> and it can cause my client to panic when running cthon basic
> tests with krb5p.
> Running faddr2line gives me:
>
> gss_krb5_checksum+0x4b6/0x630:
> ahash_request_free at
> /home/anna/Programs/linux-nfs.git/./include/crypto/hash.h:619
> (inlined by) gss_krb5_checksum at
> /home/anna/Programs/linux-nfs.git/net/sunrpc/auth_gss/gss_krb5_crypto.c:358
My diagnosis is that the memcpy() at the end of gss_krb5_checksum()
reads past the end of the buffer containing the checksum data
because the callers have ignored gss_krb5_checksum()'s API contract:
* Caller provides the truncation length of the output token (h) in
* cksumout.len.
Instead they provide the fixed length of the hmac buffer. This
length happens to be larger than the value returned by
crypto_ahash_digestsize().
Change these errant callers to work like krb5_etm_{en,de}crypt().
As a defensive measure, bound the length of the byte copy at the
end of gss_krb5_checksum().
Kunit sez:
Testing complete. Ran 68 tests: passed: 68
Elapsed time: 81.680s total, 5.875s configuring, 75.610s building, 0.103s running
Reported-by: Anna Schumaker <schumaker.anna@gmail.com>
Fixes: 8270dbfcebea ("SUNRPC: Obscure Kerberos integrity keys")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'net/sunrpc')
| -rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_crypto.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/net/sunrpc/auth_gss/gss_krb5_crypto.c b/net/sunrpc/auth_gss/gss_krb5_crypto.c index 6c7c52eeed4f..212c5d57465a 100644 --- a/net/sunrpc/auth_gss/gss_krb5_crypto.c +++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c @@ -353,7 +353,9 @@ gss_krb5_checksum(struct crypto_ahash *tfm, char *header, int hdrlen, err = crypto_ahash_final(req); if (err) goto out_free_ahash; - memcpy(cksumout->data, checksumdata, cksumout->len); + + memcpy(cksumout->data, checksumdata, + min_t(int, cksumout->len, crypto_ahash_digestsize(tfm))); out_free_ahash: ahash_request_free(req); @@ -809,8 +811,7 @@ gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset, buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN; buf->len += GSS_KRB5_TOK_HDR_LEN; - /* Do the HMAC */ - hmac.len = GSS_KRB5_MAX_CKSUM_LEN; + hmac.len = kctx->gk5e->cksumlength; hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len; /* @@ -873,8 +874,7 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len, if (ret) goto out_err; - /* Calculate our hmac over the plaintext data */ - our_hmac_obj.len = sizeof(our_hmac); + our_hmac_obj.len = kctx->gk5e->cksumlength; our_hmac_obj.data = our_hmac; ret = gss_krb5_checksum(ahash, NULL, 0, &subbuf, 0, &our_hmac_obj); if (ret) |