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Added loop check when mounting DFS tree.

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Added loop check when mounting DFS tree. mount will fail with
ELOOP if referral walks exceed MAX_NESTED_LINK count.

Signed-off-by: Igor Mammedov <niallain@gmail.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Igor Mammedov 2009-04-21 19:31:05 +04:00 committed by Steve French
parent 1af28ceb92
commit 5c2503a8e3
1 changed files with 13 additions and 0 deletions
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13
fs/cifs/connect.c
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@ -32,6 +32,7 @@
#include <linux/kthread.h>
#include <linux/pagevec.h>
#include <linux/freezer.h>
#include <linux/namei.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
#include <net/ipv6.h>
@ -2278,6 +2279,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
#ifdef CONFIG_CIFS_DFS_UPCALL
struct dfs_info3_param *referrals = NULL;
unsigned int num_referrals = 0;
int referral_walks_count = 0;
try_mount_again:
#endif
full_path = NULL;
@ -2525,6 +2527,16 @@ remote_path_check:
/* get referral if needed */
if (rc == -EREMOTE) {
#ifdef CONFIG_CIFS_DFS_UPCALL
if (referral_walks_count > MAX_NESTED_LINKS) {
/*
* BB: when we implement proper loop detection,
* we will remove this check. But now we need it
* to prevent an indefinite loop if 'DFS tree' is
* misconfigured (i.e. has loops).
*/
rc = -ELOOP;
goto mount_fail_check;
}
/* convert forward to back slashes in prepath here if needed */
if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) == 0)
convert_delimiter(cifs_sb->prepath,
@ -2558,6 +2570,7 @@ remote_path_check:
cleanup_volume_info(&volume_info);
FreeXid(xid);
kfree(full_path);
referral_walks_count++;
goto try_mount_again;
}
#else /* No DFS support, return error on mount */