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authorPavel Shilovsky <pshilovsky@samba.org>2012-05-31 13:03:26 +0400
committerSteve French <sfrench@us.ibm.com>2012-06-01 12:35:08 -0500
commit0013fb4ca3171c64a4a5d3851fb591bb575e7f04 (patch)
treee324f2926e2e920bb7355ee8dc79a09df60342cf /fs/cifs/file.c
parent51eab603f5c86dd1eae4c525df3e7f7eeab401d6 (diff)
downloadlinux-0013fb4ca3171c64a4a5d3851fb591bb575e7f04.tar.bz2
CIFS: Fix possible wrong memory allocation
when cifs_reconnect sets maxBuf to 0 and we try to calculate a size of memory we need to store locks. Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org> Signed-off-by: Steve French <sfrench@us.ibm.com>
Diffstat (limited to 'fs/cifs/file.c')
-rw-r--r--fs/cifs/file.c31
1 files changed, 25 insertions, 6 deletions
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 253170dfa716..de8abb6f7b56 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -876,7 +876,7 @@ cifs_push_mandatory_locks(struct cifsFileInfo *cfile)
struct cifsLockInfo *li, *tmp;
struct cifs_tcon *tcon;
struct cifsInodeInfo *cinode = CIFS_I(cfile->dentry->d_inode);
- unsigned int num, max_num;
+ unsigned int num, max_num, max_buf;
LOCKING_ANDX_RANGE *buf, *cur;
int types[] = {LOCKING_ANDX_LARGE_FILES,
LOCKING_ANDX_SHARED_LOCK | LOCKING_ANDX_LARGE_FILES};
@@ -892,8 +892,19 @@ cifs_push_mandatory_locks(struct cifsFileInfo *cfile)
return rc;
}
- max_num = (tcon->ses->server->maxBuf - sizeof(struct smb_hdr)) /
- sizeof(LOCKING_ANDX_RANGE);
+ /*
+ * Accessing maxBuf is racy with cifs_reconnect - need to store value
+ * and check it for zero before using.
+ */
+ max_buf = tcon->ses->server->maxBuf;
+ if (!max_buf) {
+ mutex_unlock(&cinode->lock_mutex);
+ FreeXid(xid);
+ return -EINVAL;
+ }
+
+ max_num = (max_buf - sizeof(struct smb_hdr)) /
+ sizeof(LOCKING_ANDX_RANGE);
buf = kzalloc(max_num * sizeof(LOCKING_ANDX_RANGE), GFP_KERNEL);
if (!buf) {
mutex_unlock(&cinode->lock_mutex);
@@ -1218,7 +1229,7 @@ cifs_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock, int xid)
int types[] = {LOCKING_ANDX_LARGE_FILES,
LOCKING_ANDX_SHARED_LOCK | LOCKING_ANDX_LARGE_FILES};
unsigned int i;
- unsigned int max_num, num;
+ unsigned int max_num, num, max_buf;
LOCKING_ANDX_RANGE *buf, *cur;
struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
struct cifsInodeInfo *cinode = CIFS_I(cfile->dentry->d_inode);
@@ -1228,8 +1239,16 @@ cifs_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock, int xid)
INIT_LIST_HEAD(&tmp_llist);
- max_num = (tcon->ses->server->maxBuf - sizeof(struct smb_hdr)) /
- sizeof(LOCKING_ANDX_RANGE);
+ /*
+ * Accessing maxBuf is racy with cifs_reconnect - need to store value
+ * and check it for zero before using.
+ */
+ max_buf = tcon->ses->server->maxBuf;
+ if (!max_buf)
+ return -EINVAL;
+
+ max_num = (max_buf - sizeof(struct smb_hdr)) /
+ sizeof(LOCKING_ANDX_RANGE);
buf = kzalloc(max_num * sizeof(LOCKING_ANDX_RANGE), GFP_KERNEL);
if (!buf)
return -ENOMEM;