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authorEric Biggers <ebiggers@google.com>2018-01-20 02:15:34 +0300
committerTrond Myklebust <trondmy@gmail.com>2018-01-22 18:05:11 +0300
commit49686cbbb3ebafe42e63868222f269d8053ead00 (patch)
tree4b3cbd32a2650de894100c554a75d4010edbfe20 /fs/nfs
parentcbebc6ef4fc830f4040d4140bf53484812d5d5d9 (diff)
downloadlinux-49686cbbb3ebafe42e63868222f269d8053ead00.tar.xz
NFS: reject request for id_legacy key without auxdata
nfs_idmap_legacy_upcall() is supposed to be called with 'aux' pointing to a 'struct idmap', via the call to request_key_with_auxdata() in nfs_idmap_request_key(). However it can also be reached via the request_key() system call in which case 'aux' will be NULL, causing a NULL pointer dereference in nfs_idmap_prepare_pipe_upcall(), assuming that the key description is valid enough to get that far. Fix this by making nfs_idmap_legacy_upcall() negate the key if no auxdata is provided. As usual, this bug was found by syzkaller. A simple reproducer using the command-line keyctl program is: keyctl request2 id_legacy uid:0 '' @s Fixes: 57e62324e469 ("NFS: Store the legacy idmapper result in the keyring") Reported-by: syzbot+5dfdbcf7b3eb5912abbb@syzkaller.appspotmail.com Cc: <stable@vger.kernel.org> # v3.4+ Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Trond Myklebust <trondmy@gmail.com>
Diffstat (limited to 'fs/nfs')
-rw-r--r--fs/nfs/nfs4idmap.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/nfs/nfs4idmap.c b/fs/nfs/nfs4idmap.c
index 30426c1a1bbd..22dc30a679a0 100644
--- a/fs/nfs/nfs4idmap.c
+++ b/fs/nfs/nfs4idmap.c
@@ -568,9 +568,13 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
struct idmap_msg *im;
struct idmap *idmap = (struct idmap *)aux;
struct key *key = cons->key;
- int ret = -ENOMEM;
+ int ret = -ENOKEY;
+
+ if (!aux)
+ goto out1;
/* msg and im are freed in idmap_pipe_destroy_msg */
+ ret = -ENOMEM;
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data)
goto out1;