Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix memory leaks in __check_func_call kmemleak reports this issue: unreferenced object 0xffff88817139d000 (size 2048): comm "test_progs", pid 33246, jiffies 4307381979 (age 45851.820s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [] kmalloc_trace+0x27/0xa0 [] __check_func_call+0x316/0x1230 [] check_helper_call+0x172e/0x4700 [] do_check+0x21d8/0x45e0 [] do_check_common+0x767/0xaf0 [] bpf_check+0x43e3/0x5bc0 [] bpf_prog_load+0xf26/0x1940 [] __sys_bpf+0xd2c/0x3650 [] __x64_sys_bpf+0x75/0xc0 [] do_syscall_64+0x3b/0x90 [] entry_SYSCALL_64_after_hwframe+0x63/0xcd The root case here is: In function prepare_func_exit(), the callee is not released in the abnormal scenario after "state->curframe--;". To fix, move "state->curframe--;" to the very bottom of the function, right when we free callee and reset frame[] pointer to NULL, as Andrii suggested. In addition, function __check_func_call() has a similar problem. In the abnormal scenario before "state->curframe++;", the callee also should be released by free_func_state().