From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793214187; b=UL0SG2KqUSifz6ksT+zs7wqdl15FZwcp1tWYC24rXzQAytgq3lSmHoZuhLxGdt67LCll srfgDk9fLDiJeehSA7gGa7nE7ampCRFEStjhFMeyB9cOW8HE2Eod2qHMzibmxZn6geVbO 6mhQ9BbM7pHkKLvigH0qdR4Kkcok0GKvjeALszKBOo64e/vuM2F/5fiGJOYDEpHNPrD3N /eEwpWkd+HjlSkw880TG8yhj+x9DFO4x6ozKwz1fGTKnZrOcQRRlaQALwS+/h5wk+yj0k qNcTZdW129SFCO+aq+seLbPi2nrbGJyfTigmbhEsMoayhU/56txatQdKV1QrUF4grIA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793214187; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=REueg69Tnk3HHptEc9FebJsaKUAnMBVu0svMV0Jfex8=; b=WI4k4XGut5KLHqBYpxxVeUKc2IabUGCahQaKQJifbYqGnkByeujiEzW2n91uyWxQkGFH T8w4BjIP8aXkcs+5mN7pbRS/91HCmnljipanrQbIWxBHCC4v9KTZUYFm1f15edSwVvwMC 3P/ZdshMFq2uHXJOT7c2M/k9aywDUcy+fkLrQBTVP/6fNRhAAdaGwmXwFn2mWPtKCkl/N omioI3aTFNFN/otvZcMcmhDHM7rQ1BqhzIxJjMkFbMwzBTFJy1lXt/mHXxypbneAbKlq+ IY27xr8/n+uut6s1u4C7OE984SzoQVzBAkuJFxTKMNo/Xua7baJcgXbSI1rpduzjlag== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=KPIHUTq1; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7DAAD60A3806; Wed, 28 Oct 2026 19:03:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=KPIHUTq1 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 868CB1F01828; Wed, 28 Oct 2026 19:03:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793214187; bh=REueg69Tnk3HHptEc9FebJsaKUAnMBVu0svMV0Jfex8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=KPIHUTq1psHLquYRa/VbxMCMgpqlYRkKHp37aJUBRtEjTWUHZkh6y/5vG6DlSOcun DHPv/vynHvfhoLrrqpX5ZjXkhDE/hq4RtrzxvaUYGqK5PR7Cuj/JxxZEs/izfpckpU BMuzmGL+EVLa0Dn0erZUOaFSS9FreRdyAOzDYPbY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vlad Poenaru , Yonghong Song , Martin KaFai Lau , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.1 0771/1887] bpf: Fix kmemleak warning for percpu hashmap Date: Wed, 28 Oct 2026 17:47:47 +0100 Message-ID: <20261028170516.985143055@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170459.200466217@linuxfoundation.org> References: <20261028170459.200466217@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yonghong Song [ Upstream commit 11ba7ce076e5903e7bdc1fd1498979c331b3c286 ] Vlad Poenaru reported the following kmemleak issue: unreferenced object 0x606fd7c44ac8 (size 32): backtrace (crc 0): pcpu_alloc_noprof+0x730/0xeb0 bpf_map_alloc_percpu+0x69/0xc0 prealloc_init+0x9d/0x1b0 htab_map_alloc+0x363/0x510 map_create+0x215/0x3a0 __sys_bpf+0x16b/0x3e0 __x64_sys_bpf+0x18/0x20 do_syscall_64+0x7b/0x150 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Further investigation shows the reason is due to not 8-byte aligned store of percpu pointer in htab_elem_set_ptr(): *(void __percpu **)(l->key + key_size) = pptr; Note that the whole htab_elem alignment is 8 (for x86_64). If the key_size is 4, that means pptr is stored in a location which is 4 byte aligned but not 8 byte aligned. In mm/kmemleak.c, scan_block() scans the memory based on 8 byte stride, so it won't detect above pptr, hence reporting the memory leak. In htab_map_alloc(), we already have htab->elem_size = sizeof(struct htab_elem) + round_up(htab->map.key_size, 8); if (percpu) htab->elem_size += sizeof(void *); else htab->elem_size += round_up(htab->map.value_size, 8); So storing pptr with 8-byte alignment won't cause any problem and can fix kmemleak too. The issue can be reproduced with bpf selftest as well: 1. Enable CONFIG_DEBUG_KMEMLEAK config 2. Add a getchar() before skel destroy in test_hash_map() in prog_tests/for_each.c. The purpose is to keep map available so kmemleak can be detected. 3. run './test_progs -t for_each/hash_map &' and a kmemleak should be reported. Reported-by: Vlad Poenaru Signed-off-by: Yonghong Song Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20250224175514.2207227-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/hashtab.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 56d2879c64699..36c44451b0911 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -197,12 +197,12 @@ static bool htab_is_percpu(const struct bpf_htab *htab) static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size, void __percpu *pptr) { - *(void __percpu **)(l->key + key_size) = pptr; + *(void __percpu **)(l->key + roundup(key_size, 8)) = pptr; } static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size) { - return *(void __percpu **)(l->key + key_size); + return *(void __percpu **)(l->key + roundup(key_size, 8)); } static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l) -- 2.53.0