From b4dc44b3cac9e8327e0655f530ed0c46f2e6214c Mon Sep 17 00:00:00 2001
From: Dominique Martinet <dominique.martinet@cea.fr>
Date: Sat, 8 Sep 2018 01:18:43 +0900
Subject: [PATCH] 9p locks: fix glock.client_id leak in do_lock
Git-commit: b4dc44b3cac9e8327e0655f530ed0c46f2e6214c
Patch-mainline: v4.20-rc1
References: bsc#1051510
the 9p client code overwrites our glock.client_id pointing to a static
buffer by an allocated string holding the network provided value which
we do not care about; free and reset the value as appropriate.
This is almost identical to the leak in v9fs_file_getlock() fixed by
Al Viro in commit ce85dd58ad5a6 ("9p: we are leaking glock.client_id
in v9fs_file_getlock()"), which was returned as an error by a coverity
false positive -- while we are here attempt to make the code slightly
more robust to future change of the net/9p/client code and hopefully
more clear to coverity that there is no problem.
Link: http://lkml.kernel.org/r/1536339057-21974-5-git-send-email-asmadeus@codewreck.org
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
fs/9p/vfs_file.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -208,6 +208,14 @@ static int v9fs_file_do_lock(struct file
if (schedule_timeout_interruptible(v9ses->session_lock_timeout)
!= 0)
break;
+ /*
+ * p9_client_lock_dotl overwrites flock.client_id with the
+ * server message, free and reuse the client name
+ */
+ if (flock.client_id != fid->clnt->name) {
+ kfree(flock.client_id);
+ flock.client_id = fid->clnt->name;
+ }
}
/* map 9p status to VFS status */
@@ -239,6 +247,8 @@ out_unlock:
locks_lock_file_wait(filp, fl);
fl->fl_type = fl_type;
}
+ if (flock.client_id != fid->clnt->name)
+ kfree(flock.client_id);
out:
return res;
}
@@ -273,7 +283,7 @@ static int v9fs_file_getlock(struct file
res = p9_client_getlock_dotl(fid, &glock);
if (res < 0)
- return res;
+ goto out;
/* map 9p lock type to os lock type */
switch (glock.type) {
case P9_LOCK_TYPE_RDLCK:
@@ -294,7 +304,9 @@ static int v9fs_file_getlock(struct file
fl->fl_end = glock.start + glock.length - 1;
fl->fl_pid = glock.proc_id;
}
- kfree(glock.client_id);
+out:
+ if (glock.client_id != fid->clnt->name)
+ kfree(glock.client_id);
return res;
}