| From | Ben Hutchings <> | Date | Sun, 08 Dec 2019 13:53:09 +0000 | Subject | [PATCH 3.16 25/72] smack: use GFP_NOFS while holding inode_smack::smk_lock |
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3.16.79-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Biggers <ebiggers@google.com>
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 Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> [bwh: Backported to 3.16: - Drop change to smk_netlbl_mls(), where GFP_ATOMIC is used - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- --- a/security/smack/smack_access.c +++ b/security/smack/smack_access.c @@ -430,7 +430,7 @@ char *smk_parse_smack(const char *string if (i == 0 || i >= SMK_LONGLABEL) return NULL; - smack = kzalloc(i + 1, GFP_KERNEL); + smack = kzalloc(i + 1, GFP_NOFS); if (smack != NULL) { strncpy(smack, string, i + 1); smack[i] = '\0'; @@ -502,7 +502,7 @@ struct smack_known *smk_import_entry(con if (skp != NULL) goto freeout; - skp = kzalloc(sizeof(*skp), GFP_KERNEL); + skp = kzalloc(sizeof(*skp), GFP_NOFS); if (skp == NULL) goto freeout; --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -70,7 +70,7 @@ static struct smack_known *smk_fetch(con if (ip->i_op->getxattr == NULL) return NULL; - buffer = kzalloc(SMK_LONGLABEL, GFP_KERNEL); + buffer = kzalloc(SMK_LONGLABEL, GFP_NOFS); if (buffer == NULL) return NULL;
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