NFS: Prevent memory allocation failure in nfsacl_encode()
nfsacl_encode() allocates memory in certain cases. This of course
is not guaranteed to work.
Since commit 9f06c719 "SUNRPC: New xdr_streams XDR encoder API", the
kernel's XDR encoders can't return a result indicating possibly a
failure, so a memory allocation failure in nfsacl_encode() has become
fatal (ie, the XDR code Oopses) in some cases.
However, the allocated memory is a tiny fixed amount, on the order
of 40-50 bytes. We can easily use a stack-allocated buffer for
this, with only a wee bit of nose-holding.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 39df95a..b1cf6bf 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -22,6 +22,7 @@
#include <linux/errno.h>
+EXPORT_SYMBOL(posix_acl_init);
EXPORT_SYMBOL(posix_acl_alloc);
EXPORT_SYMBOL(posix_acl_clone);
EXPORT_SYMBOL(posix_acl_valid);
@@ -32,6 +33,16 @@
EXPORT_SYMBOL(posix_acl_permission);
/*
+ * Init a fresh posix_acl
+ */
+void
+posix_acl_init(struct posix_acl *acl, int count)
+{
+ atomic_set(&acl->a_refcount, 1);
+ acl->a_count = count;
+}
+
+/*
* Allocate a new ACL with the specified number of entries.
*/
struct posix_acl *
@@ -40,10 +51,8 @@
const size_t size = sizeof(struct posix_acl) +
count * sizeof(struct posix_acl_entry);
struct posix_acl *acl = kmalloc(size, flags);
- if (acl) {
- atomic_set(&acl->a_refcount, 1);
- acl->a_count = count;
- }
+ if (acl)
+ posix_acl_init(acl, count);
return acl;
}