| Message ID | 20230916-topic-powermate_use_after_free-v1-1-2ffa46652869@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | Input: powermate - fix use-after-free in powermate_config_complete | expand |
On Mon, Sep 18, 2023 at 06:51:49AM +0200, Javier Carrasco Cruz wrote: > Hi, > > There's an obvious error in the patch I introduced when cleaningup > (urb->status should be used instead of just status). I will send a v2. I think what we need is call to usb_kill_urb(pm->config) in powermate_disconnect(), right after call to input_unregister_device(). Thanks.
Hi Javier, kernel test robot noticed the following build errors: [auto build test ERROR on 0bb80ecc33a8fb5a682236443c1e740d5c917d1d] url: https://github.com/intel-lab-lkp/linux/commits/Javier-Carrasco/Input-powermate-fix-use-after-free-in-powermate_config_complete/20230917-052943 base: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d patch link: https://lore.kernel.org/r/20230916-topic-powermate_use_after_free-v1-1-2ffa46652869%40gmail.com patch subject: [PATCH] Input: powermate - fix use-after-free in powermate_config_complete config: powerpc-ppc6xx_defconfig (https://download.01.org/0day-ci/archive/20230921/202309210232.d7MpKEIm-lkp@intel.com/config) compiler: powerpc-linux-gcc (GCC) 11.3.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230921/202309210232.d7MpKEIm-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202309210232.d7MpKEIm-lkp@intel.com/ All errors (new ones prefixed by >>): drivers/input/misc/powermate.c: In function 'powermate_config_complete': >> drivers/input/misc/powermate.c:201:21: error: 'status' undeclared (first use in this function); did you mean 'kstatfs'? 201 | if (status == -ENOENT || status == -ESHUTDOWN) | ^~~~~~ | kstatfs drivers/input/misc/powermate.c:201:21: note: each undeclared identifier is reported only once for each function it appears in vim +201 drivers/input/misc/powermate.c 192 193 /* Called when our asynchronous control message completes. We may need to issue another immediately */ 194 static void powermate_config_complete(struct urb *urb) 195 { 196 struct powermate_device *pm = urb->context; 197 unsigned long flags; 198 199 if (urb->status) { 200 printk(KERN_ERR "powermate: config urb returned %d\n", urb->status); > 201 if (status == -ENOENT || status == -ESHUTDOWN) 202 return; 203 } 204 205 spin_lock_irqsave(&pm->lock, flags); 206 powermate_sync_state(pm); 207 spin_unlock_irqrestore(&pm->lock, flags); 208 } 209
Hi Dmitry, On 19.09.23 00:10, Dmitry Torokhov wrote: > On Mon, Sep 18, 2023 at 06:51:49AM +0200, Javier Carrasco Cruz wrote: >> Hi, >> >> There's an obvious error in the patch I introduced when cleaningup >> (urb->status should be used instead of just status). I will send a v2. > > I think what we need is call to usb_kill_urb(pm->config) in > powermate_disconnect(), right after call to input_unregister_device(). > > Thanks. > That is definitely a more meaningful and elegant solution, so I will check it out and eventually send a v2 with it if everything seems ok. On the other hand usb_kill_urb() is already used on pm->irq before calling input_unregister_device(), so I would move the existing usb_kill_urb to have both calls right after the unregister_device call for code consistency, if that is alright. Thanks and best regards.
diff --git a/drivers/input/misc/powermate.c b/drivers/input/misc/powermate.c index c1c733a9cb89..f61333fea35f 100644 --- a/drivers/input/misc/powermate.c +++ b/drivers/input/misc/powermate.c @@ -196,8 +196,11 @@ static void powermate_config_complete(struct urb *urb) struct powermate_device *pm = urb->context; unsigned long flags; - if (urb->status) + if (urb->status) { printk(KERN_ERR "powermate: config urb returned %d\n", urb->status); + if (status == -ENOENT || status == -ESHUTDOWN) + return; + } spin_lock_irqsave(&pm->lock, flags); powermate_sync_state(pm);
syzbot has found a use-after-free bug [1] in the powermate driver. This happens when the device is disconnected, which leads to a memory free from the powermate_device struct. When an asynchronous control message completes after the kfree and its callback is invoked, the lock does not exist anymore and hence the bug. Return immediately if the URB status is -ESHUTDOWN (the actual status that triggered this bug) or -ENOENT, avoiding any access to potentially freed memory. [1] https://syzkaller.appspot.com/bug?extid=0434ac83f907a1dbdd1e Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com> Reported-by: syzbot+0434ac83f907a1dbdd1e@syzkaller.appspotmail.com --- drivers/input/misc/powermate.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d change-id: 20230916-topic-powermate_use_after_free-c703c7969c91 Best regards,