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author | Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> | 2020-04-30 19:02:05 +0300 |
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committer | Mimi Zohar <zohar@linux.ibm.com> | 2020-05-08 04:36:32 +0300 |
commit | 770f60586d2af0590be263f55fd079226313922c (patch) | |
tree | c0b87532373b1f8135b090a9722328d018a5fb3d /security/integrity/evm/evm_secfs.c | |
parent | 2e3a34e9f409ebe83d1af7cd2f49fca7af97dfac (diff) | |
download | linux-770f60586d2af0590be263f55fd079226313922c.tar.xz |
evm: Fix RCU list related warnings
This patch fixes the following warning and few other instances of
traversal of evm_config_xattrnames list:
[ 32.848432] =============================
[ 32.848707] WARNING: suspicious RCU usage
[ 32.848966] 5.7.0-rc1-00006-ga8d5875ce5f0b #1 Not tainted
[ 32.849308] -----------------------------
[ 32.849567] security/integrity/evm/evm_main.c:231 RCU-list traversed in non-reader section!!
Since entries are only added to the list and never deleted, use
list_for_each_entry_lockless() instead of list_for_each_entry_rcu for
traversing the list. Also, add a relevant comment in evm_secfs.c to
indicate this fact.
Reported-by: kernel test robot <lkp@intel.com>
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org> (RCU viewpoint)
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Diffstat (limited to 'security/integrity/evm/evm_secfs.c')
-rw-r--r-- | security/integrity/evm/evm_secfs.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c index 39ad1038d45d..cfc3075769bb 100644 --- a/security/integrity/evm/evm_secfs.c +++ b/security/integrity/evm/evm_secfs.c @@ -232,7 +232,14 @@ static ssize_t evm_write_xattrs(struct file *file, const char __user *buf, goto out; } - /* Guard against races in evm_read_xattrs */ + /* + * xattr_list_mutex guards against races in evm_read_xattrs(). + * Entries are only added to the evm_config_xattrnames list + * and never deleted. Therefore, the list is traversed + * using list_for_each_entry_lockless() without holding + * the mutex in evm_calc_hmac_or_hash(), evm_find_protected_xattrs() + * and evm_protected_xattr(). + */ mutex_lock(&xattr_list_mutex); list_for_each_entry(tmp, &evm_config_xattrnames, list) { if (strcmp(xattr->name, tmp->name) == 0) { |