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smack: use GFP_NOFS while holding inode_smack::smk_lock

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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>
This commit is contained in:
Eric Biggers 2019-08-21 22:54:41 -07:00 committed by Greg Kroah-Hartman
parent ef9744a021
commit 1b42503211
2 changed files with 4 additions and 4 deletions
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6
security/smack/smack_access.c
View file

@ -469,7 +469,7 @@ 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);
@ -504,7 +504,7 @@ 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;
@ -540,7 +540,7 @@ 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;

2
security/smack/smack_lsm.c
View file

@ -270,7 +270,7 @@ 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);