[PATCH v4] staging: lustre: llite: Fix variable length array warning

From: Guru Das Srinagesh
Date: Tue May 09 2017 - 02:57:23 EST


Fix sparse warning "warning: Variable length array is used." by using
kmalloc_array to allocate the required amount of memory instead and
kfree to deallocate memory after use.

Signed-off-by: Guru Das Srinagesh <gurooodas@xxxxxxxxx>
---
v4:
- Changed kmalloc_array flags from GFP_KERNEL to GFP_ATOMIC

v3:
- Fixed checkpatch warning: Comparison to NULL could be written "!fullname"

v2:
- Added missing check for NULL return value of kmalloc_array()

drivers/staging/lustre/lustre/llite/xattr.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/lustre/lustre/llite/xattr.c b/drivers/staging/lustre/lustre/llite/xattr.c
index 6187bff..ae2efd5 100644
--- a/drivers/staging/lustre/lustre/llite/xattr.c
+++ b/drivers/staging/lustre/lustre/llite/xattr.c
@@ -86,13 +86,17 @@ ll_xattr_set_common(const struct xattr_handler *handler,
const char *name, const void *value, size_t size,
int flags)
{
- char fullname[strlen(handler->prefix) + strlen(name) + 1];
+ int fullname_len = strlen(handler->prefix) + strlen(name) + 1;
+ char *fullname = kmalloc_array(fullname_len, sizeof(char), GFP_ATOMIC);
struct ll_sb_info *sbi = ll_i2sbi(inode);
struct ptlrpc_request *req = NULL;
const char *pv = value;
__u64 valid;
int rc;

+ if (!fullname)
+ return -ENOMEM;
+
if (flags == XATTR_REPLACE) {
ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_REMOVEXATTR, 1);
valid = OBD_MD_FLXATTRRM;
@@ -153,6 +157,9 @@ ll_xattr_set_common(const struct xattr_handler *handler,
}

ptlrpc_req_finished(req);
+
+ kfree(fullname);
+
return 0;
}

@@ -363,13 +370,17 @@ static int ll_xattr_get_common(const struct xattr_handler *handler,
struct dentry *dentry, struct inode *inode,
const char *name, void *buffer, size_t size)
{
- char fullname[strlen(handler->prefix) + strlen(name) + 1];
+ int fullname_len = strlen(handler->prefix) + strlen(name) + 1;
+ char *fullname = kmalloc_array(fullname_len, sizeof(char), GFP_ATOMIC);
struct ll_sb_info *sbi = ll_i2sbi(inode);
#ifdef CONFIG_FS_POSIX_ACL
struct ll_inode_info *lli = ll_i2info(inode);
#endif
int rc;

+ if (!fullname)
+ return -ENOMEM;
+
CDEBUG(D_VFSTRACE, "VFS Op:inode="DFID"(%p)\n",
PFID(ll_inode2fid(inode)), inode);

@@ -411,8 +422,12 @@ static int ll_xattr_get_common(const struct xattr_handler *handler,
return -ENODATA;
#endif
sprintf(fullname, "%s%s\n", handler->prefix, name);
- return ll_xattr_list(inode, fullname, handler->flags, buffer, size,
- OBD_MD_FLXATTR);
+
+ rc = ll_xattr_list(inode, fullname, handler->flags, buffer, size,
+ OBD_MD_FLXATTR);
+ kfree(fullname);
+
+ return rc;
}

static ssize_t ll_getxattr_lov(struct inode *inode, void *buf, size_t buf_size)
--
2.7.4