From: Zheyu Ma <zheyuma97@gmail.com> stable inclusion from stable-v4.19.247 commit ba08cbc5b53e151d0acf1930fb526fc65b7f3e65 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBP74I CVE: CVE-2022-49307 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 689ca31c542687709ba21ec2195c1fbce34fd029 ] When the driver fails at alloc_hdlcdev(), and then we remove the driver module, we will get the following splat: [ 25.065966] general protection fault, probably for non-canonical address 0xdffffc0000000182: 0000 [#1] PREEMPT SMP KASAN PTI [ 25.066914] KASAN: null-ptr-deref in range [0x0000000000000c10-0x0000000000000c17] [ 25.069262] RIP: 0010:detach_hdlc_protocol+0x2a/0x3e0 [ 25.077709] Call Trace: [ 25.077924] <TASK> [ 25.078108] unregister_hdlc_device+0x16/0x30 [ 25.078481] slgt_cleanup+0x157/0x9f0 [synclink_gt] Fix this by checking whether the 'info->netdev' is a null pointer first. Reviewed-by: Jiri Slaby <jirislaby@kernel.org> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> Link: https://lore.kernel.org/r/20220410114814.3920474-1-zheyuma97@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Cui GaoSheng <cuigaosheng1@huawei.com> --- drivers/tty/synclink_gt.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c index b88ecf102764..5d971ae3f5e5 100644 --- a/drivers/tty/synclink_gt.c +++ b/drivers/tty/synclink_gt.c @@ -1808,6 +1808,8 @@ static int hdlcdev_init(struct slgt_info *info) */ static void hdlcdev_exit(struct slgt_info *info) { + if (!info->netdev) + return; unregister_hdlc_device(info->netdev); free_netdev(info->netdev); info->netdev = NULL; -- 2.34.1