diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2020-05-28 21:38:36 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-05-29 22:25:58 +0200 |
| commit | 18644cec714aabbab173729192c7594ee57a406b (patch) | |
| tree | 044c143312f84f90aeecc7e4bd2a9dc4b5df63dd | |
| parent | d195b1d1d1196681ac4775e0361e9cca70f740c2 (diff) | |
| download | spdx-18644cec714aabbab173729192c7594ee57a406b.tar.gz | |
bpf: Fix use-after-free in fmod_ret check
Fix the following issue:
[ 436.749342] BUG: KASAN: use-after-free in bpf_trampoline_put+0x39/0x2a0
[ 436.749995] Write of size 4 at addr ffff8881ef38b8a0 by task kworker/3:5/2243
[ 436.750712]
[ 436.752677] Workqueue: events bpf_prog_free_deferred
[ 436.753183] Call Trace:
[ 436.756483] bpf_trampoline_put+0x39/0x2a0
[ 436.756904] bpf_prog_free_deferred+0x16d/0x3d0
[ 436.757377] process_one_work+0x94a/0x15b0
[ 436.761969]
[ 436.762130] Allocated by task 2529:
[ 436.763323] bpf_trampoline_lookup+0x136/0x540
[ 436.763776] bpf_check+0x2872/0xa0a8
[ 436.764144] bpf_prog_load+0xb6f/0x1350
[ 436.764539] __do_sys_bpf+0x16d7/0x3720
[ 436.765825]
[ 436.765988] Freed by task 2529:
[ 436.767084] kfree+0xc6/0x280
[ 436.767397] bpf_trampoline_put+0x1fd/0x2a0
[ 436.767826] bpf_check+0x6832/0xa0a8
[ 436.768197] bpf_prog_load+0xb6f/0x1350
[ 436.768594] __do_sys_bpf+0x16d7/0x3720
prog->aux->trampoline = tr should be set only when prog is valid.
Otherwise prog freeing will try to put trampoline via prog->aux->trampoline,
but it may not point to a valid trampoline.
Fixes: 6ba43b761c41 ("bpf: Attachment verification for BPF_MODIFY_RETURN")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: KP Singh <kpsingh@google.com>
Link: https://lore.kernel.org/bpf/20200529043839.15824-2-alexei.starovoitov@gmail.com
| -rw-r--r-- | kernel/bpf/verifier.c | 24 |
1 files changed, 11 insertions, 13 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8d7ee40e274844..bfea3f9a972fdd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10428,22 +10428,13 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) } #define SECURITY_PREFIX "security_" -static int check_attach_modify_return(struct bpf_verifier_env *env) +static int check_attach_modify_return(struct bpf_prog *prog, unsigned long addr) { - struct bpf_prog *prog = env->prog; - unsigned long addr = (unsigned long) prog->aux->trampoline->func.addr; - - /* This is expected to be cleaned up in the future with the KRSI effort - * introducing the LSM_HOOK macro for cleaning up lsm_hooks.h. - */ if (within_error_injection_list(addr) || !strncmp(SECURITY_PREFIX, prog->aux->attach_func_name, sizeof(SECURITY_PREFIX) - 1)) return 0; - verbose(env, "fmod_ret attach_btf_id %u (%s) is not modifiable\n", - prog->aux->attach_btf_id, prog->aux->attach_func_name); - return -EINVAL; } @@ -10654,11 +10645,18 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) goto out; } } + + if (prog->expected_attach_type == BPF_MODIFY_RETURN) { + ret = check_attach_modify_return(prog, addr); + if (ret) + verbose(env, "%s() is not modifiable\n", + prog->aux->attach_func_name); + } + + if (ret) + goto out; tr->func.addr = (void *)addr; prog->aux->trampoline = tr; - - if (prog->expected_attach_type == BPF_MODIFY_RETURN) - ret = check_attach_modify_return(env); out: mutex_unlock(&tr->mutex); if (ret) |