From: Leon Hwang <leon.hwang@linux.dev> mainline inclusion from mainline-v7.3-rc1 commit 61aaa8782bec59ecffd22e030f54ef9351bcabf9 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18560 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- The trampoline could be corrupted by the blindly 'tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX' in verifier. 1. A fexit attached to a tail_call_reachable prog. 'tr->flags' became 'BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_TAIL_CALL_CTX'. And, the trampoline would poke the target prog's nop insn using jmp insn instead of call insn. 2. Another fexit loaded with the same tail_call_reachable prog target. 'tr->flags' became 'BPF_TRAMP_F_TAIL_CALL_CTX'. 3. Close the first fexit link. Due to no BPF_TRAMP_F_CALL_ORIG in 'tr->flags', the trampoline will fail to restore the prog's nop insn using call insn. [ 3.410719] WARNING: kernel/bpf/syscall.c:3551 at bpf_tracing_link_release+0x53/0x60, CPU#1: test_progs/98 ... [ 3.428793] bpf_link_free+0x58/0x130 [ 3.429293] bpf_link_release+0x23/0x30 Fix the warning by updating 'tr->flags' with '|=' and lock. Fixes: 2b5dcb31a19a ("bpf, x64: Fix tailcall infinite loop") Signed-off-by: Leon Hwang <leon.hwang@linux.dev> Reviewed-by: Pu Lehui <pulehui@huawei.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/20260722151909.69142-2-leon.hwang@linux.dev Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Conflicts: include/linux/bpf.h, kernel/bpf/trampoline.c [commit aef4dfa790b22d8052cfb78044eadbe03c876c39 ("bpf: Add bpf_trampoline_multi_attach/detach functions"), 8a35e8db740f96ec17b85db5a0f83c028c707a3e ("bpf: Add struct bpf_trampoline_ops object") and e6abd4cd157bf63cd89c74f8f10abae76e7b0359 ("bpf: Use mutex lock pool for bpf trampolines") are not backport] Signed-off-by: Chen Yuxi <chenyuxi19@huawei.com> --- include/linux/bpf.h | 3 +++ kernel/bpf/trampoline.c | 7 +++++++ kernel/bpf/verifier.c | 2 +- 3 files changed, 11 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index cc2a0cc4b411..696ed5b6269f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1345,6 +1345,8 @@ struct bpf_trampoline *bpf_trampoline_get(u64 key, void bpf_trampoline_put(struct bpf_trampoline *tr); int arch_prepare_bpf_dispatcher(void *image, void *buf, s64 *funcs, int num_funcs); +void bpf_trampoline_set_flags(struct bpf_trampoline *tr, u32 flags); + /* * When the architecture supports STATIC_CALL replace the bpf_dispatcher_fn * indirection with a direct call to the bpf program. If the architecture does @@ -1452,6 +1454,7 @@ static inline bool bpf_prog_has_trampoline(const struct bpf_prog *prog) { return false; } +static inline void bpf_trampoline_set_flags(struct bpf_trampoline *tr, u32 flags) {} #endif struct bpf_func_info_aux { diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index f1bde7d021ce..fd23fdbdcf00 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -392,6 +392,13 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, int size) return ERR_PTR(err); } +void bpf_trampoline_set_flags(struct bpf_trampoline *tr, u32 flags) +{ + mutex_lock(&tr->mutex); + tr->flags |= flags; + mutex_unlock(&tr->mutex); +} + static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex) { struct bpf_tramp_image *im; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3de3edcb0344..179ace544ade 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20910,7 +20910,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) return -ENOMEM; if (tgt_prog && tgt_prog->aux->tail_call_reachable) - tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX; + bpf_trampoline_set_flags(tr, BPF_TRAMP_F_TAIL_CALL_CTX); prog->aux->dst_trampoline = tr; return 0; -- 2.34.1