github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-24 06:24:02 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

Input: zero ff_effect before compat copy in input_ff_effect_from_user

Browse Source 
In the compat path input_ff_effect_from_user() aliases the caller's
native struct ff_effect with the smaller struct ff_effect_compat and
copies only the compat sized prefix:

	compat_effect = (struct ff_effect_compat *)effect;

	if (copy_from_user(compat_effect, buffer,
			   sizeof(struct ff_effect_compat)))

The tail of the native structure is never written. Callers pass an
uninitialized on-stack object, for example evdev_do_ioctl() for
EVIOCSFF, so those bytes keep their previous stack contents.
input_ff_upload() then stores the full native structure in
ff->effects[id], from where a uinput based force feedback daemon can
read it back via UI_BEGIN_FF_UPLOAD, disclosing kernel stack memory to
userspace.

Zero the effect before the compat copy.

Fixes: 2d56f3a32c ("Input: refactor evdev 32bit compat to be shareable with uinput")
Cc: stable@vger.kernel.org
Signed-off-by: Iván Ezequiel Rodriguez <ivanrwcm25@gmail.com>
Link: https://patch.msgid.link/20260901130629.24078-3-ivanrwcm25@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Iván Ezequiel Rodriguez 2026-09-01 10:06:28 -03:00 committed by Dmitry Torokhov
parent 8b852965b8
commit f84819ef8d
1 changed files with 2 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/input/input-compat.c
View File

@ -76,6 +76,8 @@ int input_ff_effect_from_user(const char __user *buffer, size_t size,
*/
compat_effect = (struct ff_effect_compat *)effect;
memset(effect, 0, sizeof(*effect));
if (copy_from_user(compat_effect, buffer,
sizeof(struct ff_effect_compat)))
return -EFAULT;