fs: sysfs: Fix reference leak in sysfs_break_active_protection()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: fs: sysfs: Fix reference leak in sysfs_break_active_protection() The sysfs_break_active_protection() routine has an obvious reference leak in its error path. If the call to kernfs_find_and_get() fails then kn will be NULL, so the companion sysfs_unbreak_active_protection() routine won't get called (and would only cause an access violation by trying to dereference kn->parent if it was called). As a result, the reference to kobj acquired at the start of the function will never be released. Fix the leak by adding an explicit kobject_put() call when kn is NULL.

References

• https://git.kernel.org/stable/c/f28bba37fe244889b81bb5c508d3f6e5c6e342c5
• https://git.kernel.org/stable/c/57baab0f376bec8f54b0fe6beb8f77a57c228063
• https://git.kernel.org/stable/c/84bd4c2ae9c3d0a7d3a5c032ea7efff17af17e17
• https://git.kernel.org/stable/c/43f00210cb257bcb0387e8caeb4b46375d67f30c
• https://git.kernel.org/stable/c/5d43e072285e81b0b63cee7189b3357c7768a43b
• https://git.kernel.org/stable/c/ac107356aabc362aaeb77463e814fc067a5d3957
• https://git.kernel.org/stable/c/a4c99b57d43bab45225ba92d574a8683f9edc8e4
• https://git.kernel.org/stable/c/a90bca2228c0646fc29a72689d308e5fe03e6d78