This is a note to let you know that I've just added the patch titled
tty: Fix uninit-value access in ppp_sync_receive()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-fix-uninit-value-access-in-ppp_sync_receive.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 27fde9ac7db846609752e025cdc27d3146c8451f
Author: Shigeru Yoshida <syoshida@xxxxxxxxxx>
Date: Thu Nov 9 00:44:20 2023 +0900
tty: Fix uninit-value access in ppp_sync_receive()
[ Upstream commit 719639853d88071dfdfd8d9971eca9c283ff314c ]
KMSAN reported the following uninit-value access issue:
=====================================================
BUG: KMSAN: uninit-value in ppp_sync_input drivers/net/ppp/ppp_synctty.c:690 [inline]
BUG: KMSAN: uninit-value in ppp_sync_receive+0xdc9/0xe70 drivers/net/ppp/ppp_synctty.c:334
ppp_sync_input drivers/net/ppp/ppp_synctty.c:690 [inline]
ppp_sync_receive+0xdc9/0xe70 drivers/net/ppp/ppp_synctty.c:334
tiocsti+0x328/0x450 drivers/tty/tty_io.c:2295
tty_ioctl+0x808/0x1920 drivers/tty/tty_io.c:2694
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0x211/0x400 fs/ioctl.c:857
__x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
Uninit was created at:
__alloc_pages+0x75d/0xe80 mm/page_alloc.c:4591
__alloc_pages_node include/linux/gfp.h:238 [inline]
alloc_pages_node include/linux/gfp.h:261 [inline]
__page_frag_cache_refill+0x9a/0x2c0 mm/page_alloc.c:4691
page_frag_alloc_align+0x91/0x5d0 mm/page_alloc.c:4722
page_frag_alloc include/linux/gfp.h:322 [inline]
__netdev_alloc_skb+0x215/0x6d0 net/core/skbuff.c:728
netdev_alloc_skb include/linux/skbuff.h:3225 [inline]
dev_alloc_skb include/linux/skbuff.h:3238 [inline]
ppp_sync_input drivers/net/ppp/ppp_synctty.c:669 [inline]
ppp_sync_receive+0x237/0xe70 drivers/net/ppp/ppp_synctty.c:334
tiocsti+0x328/0x450 drivers/tty/tty_io.c:2295
tty_ioctl+0x808/0x1920 drivers/tty/tty_io.c:2694
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0x211/0x400 fs/ioctl.c:857
__x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
CPU: 0 PID: 12950 Comm: syz-executor.1 Not tainted 6.6.0-14500-g1c41041124bd #10
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc38 04/01/2014
=====================================================
ppp_sync_input() checks the first 2 bytes of the data are PPP_ALLSTATIONS
and PPP_UI. However, if the data length is 1 and the first byte is
PPP_ALLSTATIONS, an access to an uninitialized value occurs when checking
PPP_UI. This patch resolves this issue by checking the data length.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Shigeru Yoshida <syoshida@xxxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ppp/ppp_synctty.c b/drivers/net/ppp/ppp_synctty.c
index 047f6c68a4419..e0de8b32df46a 100644
--- a/drivers/net/ppp/ppp_synctty.c
+++ b/drivers/net/ppp/ppp_synctty.c
@@ -702,7 +702,7 @@ ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
/* strip address/control field if present */
p = skb->data;
- if (p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
+ if (skb->len >= 2 && p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
/* chop off address/control */
if (skb->len < 3)
goto err;
