[PATCH 4.14 049/125] net: 9p: initialize sun_server.sun_path to have addrs value only when addr is valid

Greg Kroah-Hartman
2020-11-03T21:10:39Z

From: Anant Thazhemadam <anant.thazhemadam@gmail.com>

[ Upstream commit 7ca1db21ef8e0e6725b4d25deed1ca196f7efb28 ]

In p9_fd_create_unix, checking is performed to see if the addr (passed
as an argument) is NULL or not.
However, no check is performed to see if addr is a valid address, i.e.,
it doesn't entirely consist of only 0's.
The initialization of sun_server.sun_path to be equal to this faulty
addr value leads to an uninitialized variable, as detected by KMSAN.
Checking for this (faulty addr) and returning a negative error number
appropriately, resolves this issue.

Link: http://lkml.kernel.org/r/20201012042404.2508-1-anant.thazhemadam@gmail.com
Reported-by: syzbot+75d51fe5bf4ebe988518@syzkaller.appspotmail.com
Tested-by: syzbot+75d51fe5bf4ebe988518@syzkaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/9p/trans_fd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index 9f020559c1928..1b56b22c5c5d7 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -1029,7 +1029,7 @@ p9_fd_create_unix(struct p9_client *client, const char *addr, char *args)

csocket = NULL;

- if (addr == NULL)
+ if (!addr || !strlen(addr))
return -EINVAL;

if (strlen(addr) >= UNIX_PATH_MAX) {
--
2.27.0