3.16.48-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Eric Biggers <[email protected]> commit 5649645d725c73df4302428ee4e02c869248b4c5 upstream. sys_add_key() and the KEYCTL_UPDATE operation of sys_keyctl() allowed a NULL payload with nonzero length to be passed to the key type's ->preparse(), ->instantiate(), and/or ->update() methods. Various key types including asymmetric, cifs.idmap, cifs.spnego, and pkcs7_test did not handle this case, allowing an unprivileged user to trivially cause a NULL pointer dereference (kernel oops) if one of these key types was present. Fix it by doing the copy_from_user() when 'plen' is nonzero rather than when '_payload' is non-NULL, causing the syscall to fail with EFAULT as expected when an invalid buffer is specified. Signed-off-by: Eric Biggers <[email protected]> Signed-off-by: David Howells <[email protected]> Signed-off-by: James Morris <[email protected]> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- security/keys/keyctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -97,7 +97,7 @@ SYSCALL_DEFINE5(add_key, const char __us payload = NULL; vm = false; - if (_payload) { + if (plen) { ret = -ENOMEM; payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN); if (!payload) { @@ -331,7 +331,7 @@ long keyctl_update_key(key_serial_t id, /* pull the payload in if one was supplied */ payload = NULL; - if (_payload) { + if (plen) { ret = -ENOMEM; payload = kmalloc(plen, GFP_KERNEL); if (!payload)
