syzbot

panic: kernel diagnostic assertion "rn != NULL" failed: file "/syzkaller/managers/multicore/kernel/sys/net/pipex.c", line 459
Starting stack trace...
panic(ffffffff833b5e41) at panic+0x1d0 sys/kern/subr_prf.c:229
__assert(ffffffff833f1c63,ffffffff83408fe6,1cb,ffffffff833a68d2) at __assert+0x29 sys/kern/subr_prf.c:-1
pipex_unlink_session_locked(ffff80002a300958) at pipex_unlink_session_locked+0x429
pipex_destroy_all_sessions(ffff8000015da000) at pipex_destroy_all_sessions+0xd9 pipex_rele_session sys/net/pipex.c:-1 [inline]
pipex_destroy_all_sessions(ffff8000015da000) at pipex_destroy_all_sessions+0xd9 sys/net/pipex.c:151
pppacclose(637e,81,2000,ffff80003c44a7f8) at pppacclose+0x16f sys/net/if_pppx.c:1335
spec_close(ffff80002a30daf0) at spec_close+0x417 sys/kern/spec_vnops.c:-1
VOP_CLOSE(fffffd805ee61880,81,fffffd80097fd478,ffff80003c44a7f8) at VOP_CLOSE+0x132 sys/kern/vfs_vops.c:156
vn_closefile(fffffd80608222f8,ffff80003c44a7f8) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline]
vn_closefile(fffffd80608222f8,ffff80003c44a7f8) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615
fdrop(fffffd80608222f8,ffff80003c44a7f8) at fdrop+0x121 sys/kern/kern_descrip.c:1280
closef(fffffd80608222f8,ffff80003c44a7f8) at closef+0x192 sys/kern/kern_descrip.c:1264
syscall(ffff80002a30dd50) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a30dd50) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:775
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x6058e92e420, count: 245
End of stack trace.
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