From 8a4f030dbced6fc255cbe67b2d0a129947e18493 Mon Sep 17 00:00:00 2001 From: Yuran Pereira Date: Wed, 8 Nov 2023 02:18:36 +0530 Subject: ptp: Fixes a null pointer dereference in ptp_ioctl Syzkaller found a null pointer dereference in ptp_ioctl originating from the lack of a null check for tsevq. ``` general protection fault, probably for non-canonical address 0xdffffc000000020b: 0000 [#1] PREEMPT SMP KASAN KASAN: probably user-memory-access in range [0x0000000000001058-0x000000000000105f] CPU: 0 PID: 5053 Comm: syz-executor353 Not tainted 6.6.0-syzkaller-10396-g4652b8e4f3ff #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023 RIP: 0010:ptp_ioctl+0xcb7/0x1d10 drivers/ptp/ptp_chardev.c:476 ... Call Trace: posix_clock_ioctl+0xf8/0x160 kernel/time/posix-clock.c:86 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl fs/ioctl.c:857 [inline] __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b ``` This patch fixes the issue by adding a check for tsevq and ensuring ptp_ioctl returns with an error if tsevq is null. Reported-by: syzbot+8a78ecea7ac1a2ea26e5@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=8a78ecea7ac1a2ea26e5 Fixes: c5a445b1e934 ("ptp: support event queue reader channel masks") Signed-off-by: Yuran Pereira Reviewed-by: Przemek Kitszel Signed-off-by: David S. Miller --- drivers/ptp/ptp_chardev.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c index 3f7a74788802..e95a6ed130ef 100644 --- a/drivers/ptp/ptp_chardev.c +++ b/drivers/ptp/ptp_chardev.c @@ -176,6 +176,8 @@ long ptp_ioctl(struct posix_clock_context *pccontext, unsigned int cmd, int enable, err = 0; tsevq = pccontext->private_clkdata; + if (!tsevq) + return -EINVAL; switch (cmd) { -- cgit v1.2.3