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| author | José Bollo <jose.bollo@open.eurogiciel.org> | 2014-04-03 13:48:41 +0200 |
|---|---|---|
| committer | Casey Schaufler <casey@schaufler-ca.com> | 2014-04-11 14:35:05 -0700 |
| commit | 9598f4c9e7069aee8639be1e04e8af26b5a77fa2 (patch) | |
| tree | 2a23f4d21a289d80e007e674cf6b7e4108404a97 /security/smack/smack_lsm.c | |
| parent | 5e9ab593c2da3064136ffa1d7f712d0e957e1958 (diff) | |
| download | lwn-9598f4c9e7069aee8639be1e04e8af26b5a77fa2.tar.gz lwn-9598f4c9e7069aee8639be1e04e8af26b5a77fa2.zip | |
SMACK: Fix handling value==NULL in post setxattr
The function `smack_inode_post_setxattr` is called each
time that a setxattr is done, for any value of name.
The kernel allow to put value==NULL when size==0
to set an empty attribute value. The systematic
call to smk_import_entry was causing the dereference
of a NULL pointer hence a KERNEL PANIC!
The problem can be produced easily by issuing the
command `setfattr -n user.data file` under bash prompt
when SMACK is active.
Moving the call to smk_import_entry as proposed by this
patch is correcting the behaviour because the function
smack_inode_post_setxattr is called for the SMACK's
attributes only if the function smack_inode_setxattr validated
the value and its size (what will not be the case when size==0).
It also has a benefical effect to not fill the smack hash
with garbage values coming from any extended attribute
write.
Change-Id: Iaf0039c2be9bccb6cee11c24a3b44d209101fe47
Signed-off-by: José Bollo <jose.bollo@open.eurogiciel.org>
Diffstat (limited to 'security/smack/smack_lsm.c')
| -rw-r--r-- | security/smack/smack_lsm.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 9a99f3c485cb..a5d86ffbf9a0 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -960,18 +960,20 @@ static void smack_inode_post_setxattr(struct dentry *dentry, const char *name, return; } - skp = smk_import_entry(value, size); if (strcmp(name, XATTR_NAME_SMACK) == 0) { + skp = smk_import_entry(value, size); if (skp != NULL) isp->smk_inode = skp->smk_known; else isp->smk_inode = smack_known_invalid.smk_known; } else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0) { + skp = smk_import_entry(value, size); if (skp != NULL) isp->smk_task = skp; else isp->smk_task = &smack_known_invalid; } else if (strcmp(name, XATTR_NAME_SMACKMMAP) == 0) { + skp = smk_import_entry(value, size); if (skp != NULL) isp->smk_mmap = skp; else |