smack: use GFP_NOFS while holding inode_smack::smk_lock

commit e5bfad3d7acc5702f32aafeb388362994f4d7bd0 upstream.

inode_smack::smk_lock is taken during smack_d_instantiate(), which is
called during a filesystem transaction when creating a file on ext4.
Therefore to avoid a deadlock, all code that takes this lock must use
GFP_NOFS, to prevent memory reclaim from waiting for the filesystem
transaction to complete.

Reported-by: syzbot+0eefc1e06a77d327a056@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index a283f9e796c114465dc969a1224e72b328a1c927..0df316c620050a89dced4115ec5a1153a7a9eab6 100644 (file)
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -474,7 +474,7 @@ char *smk_parse_smack(const char *string, int len)
        if (i == 0 || i >= SMK_LONGLABEL)
                return ERR_PTR(-EINVAL);
 
-       smack = kzalloc(i + 1, GFP_KERNEL);
+       smack = kzalloc(i + 1, GFP_NOFS);
        if (smack == NULL)
                return ERR_PTR(-ENOMEM);
 
@@ -545,7 +545,7 @@ struct smack_known *smk_import_entry(const char *string, int len)
        if (skp != NULL)
                goto freeout;
 
-       skp = kzalloc(sizeof(*skp), GFP_KERNEL);
+       skp = kzalloc(sizeof(*skp), GFP_NOFS);
        if (skp == NULL) {
                skp = ERR_PTR(-ENOMEM);
                goto freeout;

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 3055188729e621f9643a5d37047ca28feff6caea..716433e630529e74284ecef0b174251f085304d9 100644 (file)
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -268,7 +268,7 @@ static struct smack_known *smk_fetch(const char *name, struct inode *ip,
        if (ip->i_op->getxattr == NULL)
                return ERR_PTR(-EOPNOTSUPP);
 
-       buffer = kzalloc(SMK_LONGLABEL, GFP_KERNEL);
+       buffer = kzalloc(SMK_LONGLABEL, GFP_NOFS);
        if (buffer == NULL)
                return ERR_PTR(-ENOMEM);