Commit 7bed9db5 authored by Jiri Olsa's avatar Jiri Olsa Committed by Ma Wupeng
Browse files

bpf: Fix re-attachment branch in bpf_tracing_prog_attach 

stable inclusion
from stable-v6.6.14
commit 8c8bcd45e9b10eef12321f08d2e5be33d615509c
bugzilla: https://gitee.com/openeuler/kernel/issues/I99TJK

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c8bcd45e9b10eef12321f08d2e5be33d615509c



--------------------------------

commit 715d82ba636cb3629a6e18a33bb9dbe53f9936ee upstream.

The following case can cause a crash due to missing attach_btf:

1) load rawtp program
2) load fentry program with rawtp as target_fd
3) create tracing link for fentry program with target_fd = 0
4) repeat 3

In the end we have:

- prog->aux->dst_trampoline == NULL
- tgt_prog == NULL (because we did not provide target_fd to link_create)
- prog->aux->attach_btf == NULL (the program was loaded with attach_prog_fd=X)
- the program was loaded for tgt_prog but we have no way to find out which one

    BUG: kernel NULL pointer dereference, address: 0000000000000058
    Call Trace:
     <TASK>
     ? __die+0x20/0x70
     ? page_fault_oops+0x15b/0x430
     ? fixup_exception+0x22/0x330
     ? exc_page_fault+0x6f/0x170
     ? asm_exc_page_fault+0x22/0x30
     ? bpf_tracing_prog_attach+0x279/0x560
     ? btf_obj_id+0x5/0x10
     bpf_tracing_prog_attach+0x439/0x560
     __sys_bpf+0x1cf4/0x2de0
     __x64_sys_bpf+0x1c/0x30
     do_syscall_64+0x41/0xf0
     entry_SYSCALL_64_after_hwframe+0x6e/0x76

Return -EINVAL in this situation.

Fixes: f3a95075 ("bpf: Allow trampoline re-attach for tracing and lsm programs")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJiri Olsa <olsajiri@gmail.com>
Acked-by: default avatarJiri Olsa <olsajiri@gmail.com>
Acked-by: default avatarSong Liu <song@kernel.org>
Signed-off-by: default avatarDmitrii Dolgov <9erthalion6@gmail.com>
Link: https://lore.kernel.org/r/20240103190559.14750-4-9erthalion6@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarZhangPeng <zhangpeng362@huawei.com>
parent f36ba018

kernel/bpf/syscall.c

+9 −0
Original line number Diff line number Diff line
@@ -3217,6 +3217,10 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, 
	 *

	 * - if prog->aux->dst_trampoline and tgt_prog is NULL, the program

	 *   was detached and is going for re-attachment.

	 *

	 * - if prog->aux->dst_trampoline is NULL and tgt_prog and prog->aux->attach_btf

	 *   are NULL, then program was already attached and user did not provide

	 *   tgt_prog_fd so we have no way to find out or create trampoline

	 */

	if (!prog->aux->dst_trampoline && !tgt_prog) {

		/*
@@ -3230,6 +3234,11 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, 
			err = -EINVAL;

			goto out_unlock;

		}

		/* We can allow re-attach only if we have valid attach_btf. */

		if (!prog->aux->attach_btf) {

			err = -EINVAL;

			goto out_unlock;

		}

		btf_id = prog->aux->attach_btf_id;

		key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, btf_id);

	}