smack: use GFP_NOFS while holding inode_smack::smk_lock

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>

diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index f1c93a7..38ac3da 100644 (file)
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -465,7 +465,7 @@ 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);
 
@@ -500,7 +500,7 @@ int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
                        if ((m & *cp) == 0)
                                continue;
                        rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
-                                                 cat, GFP_KERNEL);
+                                                 cat, GFP_NOFS);
                        if (rc < 0) {
                                netlbl_catmap_free(sap->attr.mls.cat);
                                return rc;
@@ -536,7 +536,7 @@ 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 516f7ba..abeb09c 100644 (file)
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -288,7 +288,7 @@ static struct smack_known *smk_fetch(const char *name, struct inode *ip,
        if (!(ip->i_opflags & IOP_XATTR))
                return ERR_PTR(-EOPNOTSUPP);
 
-       buffer = kzalloc(SMK_LONGLABEL, GFP_KERNEL);
+       buffer = kzalloc(SMK_LONGLABEL, GFP_NOFS);
        if (buffer == NULL)
                return ERR_PTR(-ENOMEM);