[PATCH] ceph: fix memory leak in ceph_mds_auth_match()

[Antoine Viallon <antoine@xxxxxxxxxxxxx>]

This was detected in production because it caused a continuous memory growth,
eventually triggering kernel OOM and completely hard-locking the kernel.

Relevant kmemleak stacktrace:

    unreferenced object 0xffff888131e69900 (size 128):
      comm "git", pid 66104, jiffies 4295435999
      hex dump (first 32 bytes):
        76 6f 6c 75 6d 65 73 2f 63 6f 6e 74 61 69 6e 65  volumes/containe
        72 73 2f 67 69 74 65 61 2f 67 69 74 65 61 2f 67  rs/gitea/gitea/g
      backtrace (crc 2f3bb450):
        [<ffffffffaa68fb49>] __kmalloc_noprof+0x359/0x510
        [<ffffffffc32bf1df>] ceph_mds_check_access+0x5bf/0x14e0 [ceph]
        [<ffffffffc3235722>] ceph_open+0x312/0xd80 [ceph]
        [<ffffffffaa7dd786>] do_dentry_open+0x456/0x1120
        [<ffffffffaa7e3729>] vfs_open+0x79/0x360
        [<ffffffffaa832875>] path_openat+0x1de5/0x4390
        [<ffffffffaa834fcc>] do_filp_open+0x19c/0x3c0
        [<ffffffffaa7e44a1>] do_sys_openat2+0x141/0x180
        [<ffffffffaa7e4945>] __x64_sys_open+0xe5/0x1a0
        [<ffffffffac2cc2f7>] do_syscall_64+0xb7/0x210
        [<ffffffffac400130>] entry_SYSCALL_64_after_hwframe+0x77/0x7f

Signed-off-by: Antoine Viallon <antoine@xxxxxxxxxxxxx>
---
 fs/ceph/mds_client.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 785fe489ef4b..89c69e9c03b9 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -5702,6 +5702,9 @@ static int ceph_mds_auth_match(struct ceph_mds_client *mdsc,
 					kfree(_tpath);
 				return 0;
 			}
+
+			if (free_tpath)
+			  kfree(_tpath);
 		}
 	}
 
-- 
2.47.0