ksmbd: fix reference count leak in smb_check_perm_dacl()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix reference count leak in smb_check_perm_dacl() The issue happens in a specific path in smb_check_perm_dacl(). When "id" and "uid" have the same value, the function simply jumps out of the loop without decrementing the reference count of the object "posix_acls", which is increased by get_acl() earlier. This may result in memory leaks. Fix it by decreasing the reference count of "posix_acls" before jumping to label "check_access_bits".

References

• https://git.kernel.org/stable/c/cf824b95c12a1abacadbc2d069931963221a3414
• https://git.kernel.org/stable/c/248d71b440aef829f5cc5f6545ca113ef5062900
• https://git.kernel.org/stable/c/9758a6653c27867d810de02b4e5697163dda9883
• https://git.kernel.org/stable/c/d21a580dafc69aa04f46e6099616146a536b0724