CVE-2024-35824: misc: lis3lv02d_i2c: Fix regulators getting en-/dis-abled twice on suspend/resume

In the Linux kernel, the following vulnerability has been resolved:

misc: lis3lv02di2c: Fix regulators getting en-/dis-abled twice on suspend/resume

When not configured for wakeup lis3lv02di2csuspend() will call lis3lv02dpoweroff() even if the device has already been turned off by the runtime-suspend handler and if configured for wakeup and the device is runtime-suspended at this point then it is not turned back on to serve as a wakeup source.

Before commit b1b9f7a49440 ("misc: lis3lv02di2c: Add missing setting of the regctrl callback"), lis3lv02dpoweroff() failed to disable the regulators which as a side effect made calling poweroff() twice ok.

Now that poweroff() correctly disables the regulators, doing this twice triggers a WARN() in the regulator core:

unbalanced disables for regulator-dummy WARNING: CPU: 1 PID: 92 at drivers/regulator/core.c:2999 regulatordisable ...

Fix lis3lv02di2csuspend() to not call poweroff() a second time if already runtime-suspended and add a poweron() call when necessary to make wakeup work.

lis3lv02di2cresume() has similar issues, with an added weirness that it always powers on the device if it is runtime suspended, after which the first runtime-resume will call poweron() again, causing the enabled count for the regulator to increase by 1 every suspend/resume. These unbalanced regulatorenable() calls cause the regulator to never be turned off and trigger the following WARN() on driver unbind:

WARNING: CPU: 1 PID: 1724 at drivers/regulator/core.c:2396 regulatorput

Fix this by making lis3lv02di2cresume() mirror the new suspend().

— NVD

Linux Kernel is vulnerable to a denial of service, caused by a flaw related to regulators getting en-/dis-abled twice on suspend/resume. By sending a specially crafted request, a local authenticated attacker could exploit this vulnerability to cause a denial of service condition.

— IBM