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KEYS: DH: don't feed uninitialized "otherinfo" into KDF 

If userspace called KEYCTL_DH_COMPUTE with kdf_params containing NULL
otherinfo but nonzero otherinfolen, the kernel would allocate a buffer
for the otherinfo, then feed it into the KDF without initializing it.
Fix this by always doing the copy from userspace (which will fail with
EFAULT in this scenario).

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: James Morris <james.l.morris@oracle.com>
This commit is contained in:
Eric Biggers 2017-06-08 14:49:42 +01:00 committed by James Morris
parent bbe240454d
commit 281590b422
1 changed files with 1 additions and 1 deletions
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security/keys/dh.c
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@ -317,7 +317,7 @@ long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
* Concatenate SP800-56A otherinfo past DH shared secret -- the
* input to the KDF is (DH shared secret || otherinfo)
*/
if (kdfcopy && kdfcopy->otherinfo &&
if (kdfcopy &&
copy_from_user(kbuf + resultlen, kdfcopy->otherinfo,
kdfcopy->otherinfolen) != 0) {
ret = -EFAULT;