| Message ID | 20250422185645.1949391-1-andriy.shevchenko@linux.intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v1,1/1] Input: ALPS - bail out when device path can't fit buffer | expand |
Hi Andy, On Tue, Apr 22, 2025 at 09:56:45PM +0300, Andy Shevchenko wrote: > @@ -3094,6 +3101,16 @@ int alps_init(struct psmouse *psmouse) > > if (priv->flags & ALPS_DUALPOINT) { > struct input_dev *dev2; > + int n; > + > + n = snprintf(priv->phys2, sizeof(priv->phys2), "%s/input1", > + psmouse->ps2dev.serio->phys); > + if (n >= sizeof(priv->phys2)) { > + psmouse_err(psmouse, > + "failed to prepare path to the trackstick device\n"); > + error = -E2BIG; > + goto init_fail; So you just broke touchpad of some poor guy who had it working just fine for many years. For maximum impact you should add BUG() or panic() here. In all seriousness, it is OK to have truncated phys, rarely anyone looks at it and if we get a report of it being truncated then we can consider addressing the size (or we can decide to live with it truncated). Thanks.
On Tue, Apr 29, 2025 at 08:01:10AM +0300, Andy Shevchenko wrote: > Mon, Apr 28, 2025 at 04:30:13PM -0700, Dmitry Torokhov kirjoitti: > > On Tue, Apr 22, 2025 at 09:56:45PM +0300, Andy Shevchenko wrote: ... > > > + n = snprintf(priv->phys2, sizeof(priv->phys2), "%s/input1", > > > + psmouse->ps2dev.serio->phys); > > > + if (n >= sizeof(priv->phys2)) { > > > + psmouse_err(psmouse, > > > + "failed to prepare path to the trackstick device\n"); > > > + error = -E2BIG; > > > + goto init_fail; > > > > So you just broke touchpad of some poor guy who had it working just fine > > for many years. For maximum impact you should add BUG() or panic() > > here. > > Ha-ha. You know that your speculation most likely so far from the truth. And actually what you are telling about is not true at all. If the device was working it means that the file node name is not cut, and hence this patch won't anyhow change this behaviour. Otherwise, provide an example which can fail this and still be working in the user space. > > In all seriousness, it is OK to have truncated phys, rarely anyone looks > > at it and if we get a report of it being truncated then we can consider > > addressing the size (or we can decide to live with it truncated). > > In all seriousness, while I agree on the statement, the 4 drivers in Input > subsystem break the build. It's the biggest obstacle now to enable WERROR=y, > which is default, builds on `make W=1`. So, I already gave you chance to fix, > instead I hear nothing back for a months (to be precise 2 months and a day > passed from my first attempt that you didn't like), the problem still exists. > Please, address this the way you like. For the reference, the first approach: https://lore.kernel.org/r/20250228121147.242115-1-andriy.shevchenko@linux.intel.com where I also asked about this one, ano got no answer. I really don't want to try anything new as it seems a big pushback to whatever I propose. So, please consider fixing the issues rather sooner. I will be more than happy to test.
diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c index 0bd7b09b0aa3..e76dcb19fa72 100644 --- a/drivers/input/mouse/alps.c +++ b/drivers/input/mouse/alps.c @@ -1401,6 +1401,16 @@ static int alps_do_register_bare_ps2_mouse(struct alps_data *priv) struct psmouse *psmouse = priv->psmouse; struct input_dev *dev3; int error; + int n; + + n = snprintf(priv->phys3, sizeof(priv->phys3), "%s/%s", + psmouse->ps2dev.serio->phys, + priv->dev2 ? "input2" : "input1"); + if (n >= sizeof(priv->phys3)) { + psmouse_err(psmouse, + "failed to prepare path to the secondary device\n"); + return -E2BIG; + } dev3 = input_allocate_device(); if (!dev3) { @@ -1408,9 +1418,6 @@ static int alps_do_register_bare_ps2_mouse(struct alps_data *priv) return -ENOMEM; } - snprintf(priv->phys3, sizeof(priv->phys3), "%s/%s", - psmouse->ps2dev.serio->phys, - (priv->dev2 ? "input2" : "input1")); dev3->phys = priv->phys3; /* @@ -3094,6 +3101,16 @@ int alps_init(struct psmouse *psmouse) if (priv->flags & ALPS_DUALPOINT) { struct input_dev *dev2; + int n; + + n = snprintf(priv->phys2, sizeof(priv->phys2), "%s/input1", + psmouse->ps2dev.serio->phys); + if (n >= sizeof(priv->phys2)) { + psmouse_err(psmouse, + "failed to prepare path to the trackstick device\n"); + error = -E2BIG; + goto init_fail; + } dev2 = input_allocate_device(); if (!dev2) { @@ -3103,8 +3120,6 @@ int alps_init(struct psmouse *psmouse) goto init_fail; } - snprintf(priv->phys2, sizeof(priv->phys2), "%s/input1", - psmouse->ps2dev.serio->phys); dev2->phys = priv->phys2; /*
When creating a physical device name in the driver the snprintf() takes an up to 32 characters argument along with the additional 8 characters and tries to pack this into 32 bytes array. GCC complains about that when build with `make W=1`: drivers/input/mouse/alps.c:1411:9: note: ‘snprintf’ output between 8 and 39 bytes into a destination of size 32 1411 | snprintf(priv->phys3, sizeof(priv->phys3), "%s/%s", | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1412 | psmouse->ps2dev.serio->phys, | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1413 | (priv->dev2 ? "input2" : "input1")); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/input/mouse/alps.c:3106:17: note: ‘snprintf’ output between 8 and 39 bytes into a destination of size 32 3106 | snprintf(priv->phys2, sizeof(priv->phys2), "%s/input1", | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3107 | psmouse->ps2dev.serio->phys); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fix these by checking for the potential overflow. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> --- drivers/input/mouse/alps.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-)