From: Eric Biggers ebiggers@google.com
This patch has been added to the stable tree. If you have any objections, please let us know.
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[ Upstream commit 5649645d725c73df4302428ee4e02c869248b4c5 ]
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.
Cc: stable@vger.kernel.org # 2.6.10+ Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: James Morris james.l.morris@oracle.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- security/keys/keyctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index a2d29cca16c6..c804189d0d03 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -99,7 +99,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, payload = NULL;
vm = false; - if (_payload) { + if (plen) { ret = -ENOMEM; payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN); if (!payload) { @@ -333,7 +333,7 @@ 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)