Description: pid: take a reference when initializing `cad_pid`
References:
Notes:
 carnil> Introduced in 9ec52099e4b8678a ("[PATCH] replace cad_pid by a struct pid").
 carnil> Vulnerable versions: 2.6.19-rc1.
Bugs:
upstream: released (5.13-rc5) [0711f0d7050b9e07c44bc159bbc64ac0a1022c7f]
6.7-upstream-stable: N/A "Fixed before branching point"
6.6-upstream-stable: N/A "Fixed before branching point"
6.1-upstream-stable: N/A "Fixed before branching point"
5.10-upstream-stable: released (5.10.43) [7178be006d495ffb741c329012da289b62dddfe6]
4.19-upstream-stable: released (4.19.194) [d106f05432e60f9f62d456ef017687f5c73cb414]
sid: released (5.10.46-1)
6.1-bookworm-security: N/A "Fixed before branching point"
5.10-bullseye-security: N/A "Fixed before branching point"
4.19-buster-security: released (4.19.194-1)