From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 667F0368D5A; Sat, 12 Sep 2026 07:55:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789199742; cv=none; b=fXJ4jVTiDygBcCrJqDN43adUWUvICy/F1WjcHvvURy9wVr8G3VBT9e3ImEptAv5WdbCwH/UsOVvv7wslD/dJLX7mSMCgya5Y/VmnLJbKwMAXRhZzIhyRGWvhW29+05GxncZJY3Ad/1JQjf5BDOLOQi+8o5ns+BNmuSmz+uPIoc8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789199742; c=relaxed/simple; bh=OtnRbOaY0hzsTNWqZlo5Ns3E36fgahZ9E1QIYrhfarg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LNqyoPS9XqFE7ZIXeKWFUbl4eJZujAkjhXpdDmpN7X8jcmJ9WKQq90D6et+Ev2+GWh0eLb7cw5jlXZSK65ynAQrXcb4R2pwfELAW933ybiNVPe8+4DO87waGSRiCzLlUc6Nbz6ZpAXumVUv9LDwf2BfV83H61lZQkUco7b0hpoY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=p0wA13/e; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="p0wA13/e" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F13FA1F000FF; Sat, 12 Sep 2026 07:55:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789199741; bh=l4Udm6oZGLi5OANCRy613WHp7nXBSu+lxQIz/FgNONE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=p0wA13/eojcJE17h+RRNxWnkLXUYStkU3j9umFyyoI0vqwggRA2rDHj9ez0+eq6Ud OHPfoz9yc+jPETn3ghzlgDXzWTYvWjcmWTUZXrzTU3gBOSM4U38kjp2VXQFhTwZS3r Qpz9KZlwk6sz/ToTblqxphQUvbp64H77oX5z45e0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Leon Hwang , Pu Lehui , Jiri Olsa , Kumar Kartikeya Dwivedi , Sasha Levin Subject: [PATCH 7.2 0648/1815] bpf: Fix WARNING in bpf_tracing_link_release Date: Sat, 12 Sep 2026 08:39:58 +0200 Message-ID: <20260912065704.092285604@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065648.999753832@linuxfoundation.org> References: <20260912065648.999753832@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Leon Hwang [ Upstream commit 61aaa8782bec59ecffd22e030f54ef9351bcabf9 ] 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 Reviewed-by: Pu Lehui Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20260722151909.69142-2-leon.hwang@linux.dev Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Sasha Levin --- include/linux/bpf.h | 2 ++ kernel/bpf/trampoline.c | 7 +++++++ kernel/bpf/verifier.c | 2 +- 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 31c1fef6b59b1..52eedb71d6eb7 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1524,6 +1524,7 @@ int bpf_trampoline_multi_attach(struct bpf_prog *prog, u32 *ids, struct bpf_tracing_multi_link *link); int bpf_trampoline_multi_detach(struct bpf_prog *prog, struct bpf_tracing_multi_link *link); +void bpf_trampoline_set_flags(struct bpf_trampoline *tr, u32 flags); /* * When the architecture supports STATIC_CALL replace the bpf_dispatcher_fn @@ -1647,6 +1648,7 @@ static inline int bpf_trampoline_multi_detach(struct bpf_prog *prog, { return -ENOTSUPP; } +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 6eadf64f7ec90..129d07db117ec 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -670,6 +670,13 @@ 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) +{ + trampoline_lock(tr); + tr->flags |= flags; + trampoline_unlock(tr); +} + static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex, const struct bpf_trampoline_ops *ops, void *data) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 22a122403a2e3..072275c7d4be6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -19444,7 +19444,7 @@ 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; -- 2.53.0