From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A1B088F40 for ; Sun, 16 Jul 2023 20:33:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27162C433C7; Sun, 16 Jul 2023 20:33:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689539616; bh=2oB4vB1Efmgfih9AVNTrT5FnbnEcjbX/SqODJya6r6I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QV5R18irwQUykW3qtTH710ENUOIB53XwnTIHbJcy++pMuJEC3VQsMftak8jic5dDz lwMg70fo8d0XU6MqHMfRDS1JES/CArgE/moQ2HkiaUmO4VGz40cT7+Vj11KZzVUVGE ZEJdfBCuT7jeac9fAX9LhWnbLMMH/X8I4yLNYvTM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Martin KaFai Lau , Daniel Borkmann , Yonghong Song , Sasha Levin Subject: [PATCH 6.1 070/591] libbpf: btf_dump_type_data_check_overflow needs to consider BTF_MEMBER_BITFIELD_SIZE Date: Sun, 16 Jul 2023 21:43:29 +0200 Message-ID: <20230716194925.693820203@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230716194923.861634455@linuxfoundation.org> References: <20230716194923.861634455@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Martin KaFai Lau [ Upstream commit c39028b333f3a3a765c5c0b9726b8e38aedf0ba1 ] The btf_dump/struct_data selftest is failing with: [...] test_btf_dump_struct_data:FAIL:unexpected return value dumping fs_context unexpected unexpected return value dumping fs_context: actual -7 != expected 264 [...] The reason is in btf_dump_type_data_check_overflow(). It does not use BTF_MEMBER_BITFIELD_SIZE from the struct's member (btf_member). Instead, it is using the enum size which is 4. It had been working till the recent commit 4e04143c869c ("fs_context: drop the unused lsm_flags member") removed an integer member which also removed the 4 bytes padding at the end of the fs_context. Missing this 4 bytes padding exposed this bug. In particular, when btf_dump_type_data_check_overflow() reaches the member 'phase', -E2BIG is returned. The fix is to pass bit_sz to btf_dump_type_data_check_overflow(). In btf_dump_type_data_check_overflow(), it does a different size check when bit_sz is not zero. The current fs_context: [3600] ENUM 'fs_context_purpose' encoding=UNSIGNED size=4 vlen=3 'FS_CONTEXT_FOR_MOUNT' val=0 'FS_CONTEXT_FOR_SUBMOUNT' val=1 'FS_CONTEXT_FOR_RECONFIGURE' val=2 [3601] ENUM 'fs_context_phase' encoding=UNSIGNED size=4 vlen=7 'FS_CONTEXT_CREATE_PARAMS' val=0 'FS_CONTEXT_CREATING' val=1 'FS_CONTEXT_AWAITING_MOUNT' val=2 'FS_CONTEXT_AWAITING_RECONF' val=3 'FS_CONTEXT_RECONF_PARAMS' val=4 'FS_CONTEXT_RECONFIGURING' val=5 'FS_CONTEXT_FAILED' val=6 [3602] STRUCT 'fs_context' size=264 vlen=21 'ops' type_id=3603 bits_offset=0 'uapi_mutex' type_id=235 bits_offset=64 'fs_type' type_id=872 bits_offset=1216 'fs_private' type_id=21 bits_offset=1280 'sget_key' type_id=21 bits_offset=1344 'root' type_id=781 bits_offset=1408 'user_ns' type_id=251 bits_offset=1472 'net_ns' type_id=984 bits_offset=1536 'cred' type_id=1785 bits_offset=1600 'log' type_id=3621 bits_offset=1664 'source' type_id=42 bits_offset=1792 'security' type_id=21 bits_offset=1856 's_fs_info' type_id=21 bits_offset=1920 'sb_flags' type_id=20 bits_offset=1984 'sb_flags_mask' type_id=20 bits_offset=2016 's_iflags' type_id=20 bits_offset=2048 'purpose' type_id=3600 bits_offset=2080 bitfield_size=8 'phase' type_id=3601 bits_offset=2088 bitfield_size=8 'need_free' type_id=67 bits_offset=2096 bitfield_size=1 'global' type_id=67 bits_offset=2097 bitfield_size=1 'oldapi' type_id=67 bits_offset=2098 bitfield_size=1 Fixes: 920d16af9b42 ("libbpf: BTF dumper support for typed data") Signed-off-by: Martin KaFai Lau Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20230428013638.1581263-1-martin.lau@linux.dev Signed-off-by: Sasha Levin --- tools/lib/bpf/btf_dump.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c index 4cd1d49c94d6d..713264899250a 100644 --- a/tools/lib/bpf/btf_dump.c +++ b/tools/lib/bpf/btf_dump.c @@ -2213,9 +2213,25 @@ static int btf_dump_type_data_check_overflow(struct btf_dump *d, const struct btf_type *t, __u32 id, const void *data, - __u8 bits_offset) + __u8 bits_offset, + __u8 bit_sz) { - __s64 size = btf__resolve_size(d->btf, id); + __s64 size; + + if (bit_sz) { + /* bits_offset is at most 7. bit_sz is at most 128. */ + __u8 nr_bytes = (bits_offset + bit_sz + 7) / 8; + + /* When bit_sz is non zero, it is called from + * btf_dump_struct_data() where it only cares about + * negative error value. + * Return nr_bytes in success case to make it + * consistent as the regular integer case below. + */ + return data + nr_bytes > d->typed_dump->data_end ? -E2BIG : nr_bytes; + } + + size = btf__resolve_size(d->btf, id); if (size < 0 || size >= INT_MAX) { pr_warn("unexpected size [%zu] for id [%u]\n", @@ -2370,7 +2386,7 @@ static int btf_dump_dump_type_data(struct btf_dump *d, { int size, err = 0; - size = btf_dump_type_data_check_overflow(d, t, id, data, bits_offset); + size = btf_dump_type_data_check_overflow(d, t, id, data, bits_offset, bit_sz); if (size < 0) return size; err = btf_dump_type_data_check_zero(d, t, id, data, bits_offset, bit_sz); -- 2.39.2